396 lines
14 KiB
Markdown
396 lines
14 KiB
Markdown
# 序列化
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  Convert提供Java对象的序列化与反序列化功能。支持JSON(JavaScript Object Notation)、BSON(Binary Stream Object Notation)、PROTOBUF三种格式化。 三种格式使用方式完全一样，其性能都大幅度超过其他JSON框架。同时JSON内置于HTTP服务中，BSON也是SNCP协议数据序列化的基础。
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## 基本API
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  JSON序列化其操作类主要是JsonConvert，配置类主要是JsonFactory、ConvertColumn。JsonFactory采用同ClassLoader类似的双亲委托方式设计。
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JsonConvert 序列化encode方法：
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```java
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public String convertTo(Object value);
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public String convertTo(Type type, Object value);
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public void convertTo(OutputStream out, Object value);
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public void convertTo(OutputStream out, Type type, Object value);
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public ByteBuffer[] convertTo(Supplier<ByteBuffer> supplier, Object value);
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public ByteBuffer[] convertTo(Supplier<ByteBuffer> supplier, Type type, Object value);
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public void convertTo(JsonWriter writer, Object value);
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public void convertTo(JsonWriter writer, Type type, Object value);
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```
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JsonConvert 反序列化decode方法：
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```java
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public <T> T convertFrom(Type type, String text);
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public <T> T convertFrom(Type type, char[] text);
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public <T> T convertFrom(Type type, char[] text, int start, int len);
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public <T> T convertFrom(Type type, InputStream in);
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public <T> T convertFrom(Type type, ByteBuffer... buffers);
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public <T> T convertFrom(Type type, JsonReader reader);
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```
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## JSON基本用法
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```java
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@Data
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public class UserRecord {
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private int userid;
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private String username = "";
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private String password = "";
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public UserRecord() {
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}
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}
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public static void main(String[] args) throws Exception {
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UserRecord user = new UserRecord();
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user.setUserid(100);
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user.setUsername("redkalename");
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user.setPassword("123456");
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final JsonConvert convert = JsonConvert.root();
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String json = convert.convertTo(user);
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System.out.println(json); //应该是 {"password":"123456","userid":100,"username":"redkalename"}
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UserRecord user2 = convert.convertFrom(UserRecord.class, json);
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System.out.println(convert.convertTo(user2)); //应该也是 {"password":"123456","userid":100,"username":"redkalename"}
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/**
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* 以下功能是为了屏蔽password字段。
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* 等价于 public String getPassword() 加上 @ConvertColumn ：
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*
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* @ConvertColumn(ignore = true, type = ConvertType.JSON)
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* public String getPassword() {
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* return password;
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* }
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**/
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final JsonFactory childFactory = JsonFactory.root().createChild();
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childFactory.register(UserRecord.class, true, "password"); //屏蔽掉password字段使其不输出
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childFactory.reloadCoder(UserRecord.class); //重新加载Coder使之覆盖父Factory的配置
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final JsonConvert childConvert = childFactory.getConvert();
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json = childConvert.convertTo(user);
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System.out.println(json); //应该是 {"userid":100,"username":"redkalename"}
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user2 = childConvert.convertFrom(UserRecord.class, json);
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System.out.println(childConvert.convertTo(user2)); //应该也是 {"userid":100,"username":"redkalename"}
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}
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```
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  在Redkale里存在默认的JsonConvert、BsonConvert、ProtobufConvert对象。 只需在所有Service、Servlet中增加依赖注入资源。
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```java
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public class XXXService implements Service {
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@Resource
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private JsonConvert jsonConvert;
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@Resource
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private BsonConvert bsonConvert;
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@Resource
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private ProtobufConvert protobufConvert;
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}
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public class XXXServlet extends HttpServlet {
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@Resource
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private JsonConvert jsonConvert;
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@Resource
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private BsonConvert bsonConvert;
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@Resource
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private ProtobufConvert protobufConvert;
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}
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```
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   同一类型数据通过设置新的JsonFactory可以有不同的输出。
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```java
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@Data
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public class UserSimpleInfo {
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private int userid;
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private String username = "";
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@ConvertColumn(ignore = true, type = ConvertType.JSON)
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private long regtime; //注册时间
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@ConvertColumn(ignore = true, type = ConvertType.JSON)
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private String regaddr = ""; //注册IP
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}
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public class UserInfoServlet extends HttpBaseServlet {
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@Resource
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private UserSerice service;
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@Resource
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private JsonFactory jsonRootFactory;
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@Resource
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private JsonConvert detailConvert;
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@Override
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public void init(HttpContext context, AnyValue config) {
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final JsonFactory childFactory = jsonRootFactory.createChild();
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childFactory.register(UserSimpleInfo.class, false, "regtime", "regaddr"); //允许输出注册时间与注册地址
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childFactory.reloadCoder(UserSimpleInfo.class); //重新加载Coder使之覆盖父Factory的配置
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this.detailConvert = childFactory.getConvert();
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}
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// 获取他人基本信息
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@HttpMapping(url = "/user/info/")
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public void info(HttpRequest req, HttpResponse resp) throws IOException {
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int userid = Integer.parseInt(req.getRequstURILastPath());
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UserSimpleInfo user = service.findUserInfo(userid);
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resp.finishJson(user); // 不包含用户的注册时间和注册地址字段信息
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}
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//获取用户自己的信息
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@HttpMapping(url = "/user/myinfo")
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public void mydetail(HttpRequest req, HttpResponse resp) throws IOException {
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int userid = req.currentUser().getUserid(); //获取当前用户ID
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UserSimpleInfo user = service.findUserInfo(userid);
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resp.finishJson(detailConvert, user); // 包含用户的注册时间和注册地址字段信息
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}
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}
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```
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  Convert 支持带参数构造函数。
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    1. public 带参数的构造函数加上 @ConstructorParameters 注解：
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```java
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public class UserRecord {
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private int userid;
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private String username = "";
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private String password = "";
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@ConstructorParameters({"userid", "username", "password"})
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public UserRecord(int userid, String username, String password) {
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this.userid = userid;
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this.username = username;
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this.password = password;
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}
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public int getUserid() {
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return userid;
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}
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public String getUsername() {
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return username;
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}
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public String getPassword() {
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return password;
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}
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}
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```
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    2. 自定义Creator：
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```java
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public class UserRecord {
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private int userid;
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private String username = "";
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private String password = "";
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UserRecord(int userid, String username, String password) {
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this.userid = userid;
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this.username = username;
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this.password = password;
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}
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public int getUserid() {
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return userid;
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}
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public String getUsername() {
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return username;
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}
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public String getPassword() {
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return password;
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}
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/**
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* 自定义Creator方法。
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* 1) 方法名可以随意。
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* 2) 方法必须是static。
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* 3）方法的参数必须为空。
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* 4）方法的返回类型必须是Creator。
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*
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* @return
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*/
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private static Creator<UserRecord> creator() {
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return new Creator<UserRecord>() {
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@Override
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@ConstructorParameters({"userid", "username", "password"}) //带参数的构造函数必须有ConstructorParameters注解
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public UserRecord create(Object... params) {
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return new UserRecord((params[0] == null ? 0 : (Integer) params[0]), (String) params[1], (String) params[2]);
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}
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};
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}
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}
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```
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  通常JavaBean类默认有个public空参数的构造函数，因此大部分情况下不要自定义Creator，其实只要不是private的空参数构造函数Convert都能自动支持(其他的框架都仅支持public的构造函数)，只有仅含private的构造函数才需要自定义Creator。带参数的构造函数就需要标记@ConstructorParameters，常见于Immutable Object。
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## 自定义
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  Convert 支持自定义Decode、Encode。
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    1. 通过ConvertFactory显式的注册：
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```java
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public class FileSimpleCoder<R extends Reader, W extends Writer> extends SimpledCoder<R, W, File> {
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public static final FileSimpleCoder instance = new FileSimpleCoder();
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@Override
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public void convertTo(W out, File value) {
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out.writeString(value == null ? null : value.getPath());
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}
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@Override
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public File convertFrom(R in) {
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String path = in.readString();
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return path == null ? null : new File(path);
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}
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}
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JsonFactory.root().register(File.class, FileSimpleCoder.instance);
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BsonFactory.root().register(File.class, FileSimpleCoder.instance);
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```
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    2. 通过JavaBean类自定义静态方法自动加载：
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```java
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public class InnerCoderEntity {
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private final String val;
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private final int id;
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private InnerCoderEntity(int id, String value) {
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this.id = id;
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this.val = value;
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}
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public static InnerCoderEntity create(int id, String value) {
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return new InnerCoderEntity(id, value);
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}
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/**
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* 该方法提供给Convert组件自动加载。
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* 1) 方法名可以随意。
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* 2) 方法必须是static
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* 3）方法的参数有且只能有一个， 且必须是org.redkale.convert.ConvertFactory或子类。
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* —3.1) 参数类型为org.redkale.convert.ConvertFactory 表示适合JSON和BSON。
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* —3.2) 参数类型为org.redkale.convert.json.JsonFactory 表示仅适合JSON。
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* —3.3) 参数类型为org.redkale.convert.bson.BsonFactory 表示仅适合BSON。
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* 4）方法的返回类型必须是org.redkale.convert.Decodeable/org.redkale.convert.Encodeable/org.redkale.convert.SimpledCoder
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* 若返回类型不是org.redkale.convert.SimpledCoder, 就必须提供两个方法： 一个返回Decodeable 一个返回 Encodeable。
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*
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* @param factory
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* @return
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*/
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private static SimpledCoder<Reader, Writer, InnerCoderEntity> createConvertCoder(final ConvertFactory factory) {
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return new SimpledCoder<Reader, Writer, InnerCoderEntity>() {
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//必须与EnMember[] 顺序一致
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private final DeMember[] deMembers = new DeMember[]{
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DeMember.create(factory, InnerCoderEntity.class, "id"),
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DeMember.create(factory, InnerCoderEntity.class, "val")};
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//必须与DeMember[] 顺序一致
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private final EnMember[] enMembers = new EnMember[]{
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EnMember.create(factory, InnerCoderEntity.class, "id"),
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EnMember.create(factory, InnerCoderEntity.class, "val")};
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@Override
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public void convertTo(Writer out, InnerCoderEntity value) {
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if (value == null) {
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out.writeObjectNull(InnerCoderEntity.class);
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return;
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}
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out.writeObjectB(value);
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for (EnMember member : enMembers) {
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out.writeObjectField(member, value);
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}
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out.writeObjectE(value);
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}
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@Override
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public InnerCoderEntity convertFrom(Reader in) {
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if (in.readObjectB(InnerCoderEntity.class) == null) return null;
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int index = 0;
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final Object[] params = new Object[deMembers.length];
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while (in.hasNext()) {
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DeMember member = in.readFieldName(deMembers); //读取字段名
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in.readBlank(); //读取字段名与字段值之间的间隔符，JSON则是跳过冒号:
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if (member == null) {
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in.skipValue(); //跳过不存在的字段的值, 一般不会发生
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} else {
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params[index++] = member.read(in);
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}
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}
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in.readObjectE(InnerCoderEntity.class);
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return InnerCoderEntity.create(params[0] == null ? 0 : (Integer) params[0], (String) params[1]);
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}
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};
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}
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public int getId() {
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return id;
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}
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public String getVal() {
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return val;
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}
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@Override
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public String toString() {
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return JsonConvert.root().convertTo(this);
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}
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}
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```
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## BSON数据格式
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  BSON类似Java自带的Serializable， 其格式如下:
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    1). 基本数据类型: 直接转换成byte[]
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    2). SmallString(无特殊字符且长度小于256的字符串): length(1 byte) + byte[](utf8); 通常用于类名、字段名、枚举。
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    3). String: length(4 bytes) + byte[](utf8);
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    4). 数组: length(4 bytes) + byte[]...
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    5). Object:
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      1. realclass (SmallString) (如果指定格式化的class与实体对象的class不一致才会有该值, 该值可以使用@ConvertEntity给其取个别名)
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      2. 空字符串(SmallString)
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      3. SIGN_OBJECTB 标记位，值固定为0xBB (short)
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      4. 循环字段值:
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        4.1 SIGN_HASNEXT 标记位，值固定为1 (byte)
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        4.2 字段类型; 1-9为基本类型&字符串; 101-109为基本类型&字符串的数组; 127为Object
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        4.3 字段名 (SmallString)
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        4.4 字段的值Object
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      5. SIGN_NONEXT 标记位，值固定为0 (byte)
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       6. SIGN_OBJECTE 标记位，值固定为0xEE (short)
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