public interface ConverterFactory<S, R> {
  //將S類型的對象轉(zhuǎn)換為T類型，R為目標(biāo)類型T的基類
  <T extends R> Converter<S, T> getConverter(Class<T> targetType);
}

public interface GenericConverter {

  //ConvertiblePair包含了源類型和目標(biāo)類型，它的定義在下面
  Set<ConvertiblePair> getConvertibleTypes();

  //TypeDescriptor包含了需轉(zhuǎn)換類型對象所在宿主類的信息，我們根據(jù)此信息，完成源到目標(biāo)類型的轉(zhuǎn)換
  Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType);


  /**
   * 內(nèi)部類定義
   */
  public static final class ConvertiblePair {
    //源類型
    private final Class<?> sourceType;
    //目標(biāo)類類型
    private final Class<?> targetType;

    /**
     * 創(chuàng)建一個(gè)源-目標(biāo)對子
     */
    public ConvertiblePair(Class<?> sourceType, Class<?> targetType) {
      Assert.notNull(sourceType, "Source type must not be null");
      Assert.notNull(targetType, "Target type must not be null");
      this.sourceType = sourceType;
      this.targetType = targetType;
    }

    public Class<?> getSourceType() {
      return this.sourceType;
    }

    public Class<?> getTargetType() {
      return this.targetType;
    }
    //忽略hashCode\equals\toString等重寫方法
  }
}

public interface ConditionalGenericConverter extends GenericConverter, ConditionalConverter {
}

public interface ConditionalConverter {
  /**
   * Should the conversion from {@code sourceType} to {@code targetType} currently under
   */
  //根據(jù)源類型和目標(biāo)類型所在宿主類型的上下文信息判斷是否要進(jìn)行類型轉(zhuǎn)換
  boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType);
}

public interface ConverterFactory<S, R> {

  //獲取將源類轉(zhuǎn)換為特定R類或其子類的轉(zhuǎn)換器
  <T extends R> Converter<S, T> getConverter(Class<T> targetType);

}

package org.springframework.core.convert;

public interface ConversionService {

  //判斷sourceType是否可以轉(zhuǎn)換為targetType
  boolean canConvert(Class<?> sourceType, Class<?> targetType);

  //TypeDescriptor描述了轉(zhuǎn)換類的各類上下文信息，在類型轉(zhuǎn)換實(shí)現(xiàn)方法中可以根據(jù)這些信息進(jìn)行靈活控制
  //比如這里通過源類和目標(biāo)類的上下文信息判斷是否可以進(jìn)行轉(zhuǎn)換
  boolean canConvert(TypeDescriptor sourceType, TypeDescriptor targetType);

  //將source轉(zhuǎn)換為targetType
  <T> T convert(Object source, Class<T> targetType);

  //利用源、目標(biāo)類的上下文信息，將源類型轉(zhuǎn)換為目標(biāo)類型
  Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType);

}

public class MyConvertor implements Converter<String, User>{

  @Override
  public User convert(String source) {//source為要轉(zhuǎn)換的字符串
    String[] values = source.split(",");//根據(jù)我們的需求，用逗號來區(qū)分
    Integer id = Integer.valueOf(values[0]);
    User user = new User(id,values[1],values[2]);
    return user;
  }
}
/**********下面是我們的UserPOJO類**********/
public class User {
  public User() {
    super();
  }
  private Integer id;
  private String userName;
  private String password;
  public Integer getId() {
    return id;
  }
  public void setId(Integer id) {
    this.id = id;
  }
  public User(Integer id, String userName, String password) {
    super();
    this.id = id;
    this.userName = userName;
    this.password = password;
  }
  //忽略get和set方法
  @Override
  public String toString() {
    return "User [id=" + id + ", userName=" + userName + ", password="
        + password + "]";
  }

}

<!-- 通過:annotation-driven的conversion-service屬性來裝配我們的類型轉(zhuǎn)換器 -->
<mvc:annotation-driven conversion-service="factoryBean" />
<!-- 通過ConversionServiceFactoryBean注冊我們的自定義轉(zhuǎn)換器 -->
<bean class="org.springframework.context.support.ConversionServiceFactoryBean" id="factoryBean" >
  <property name="converters"><!-- 在屬性converters注冊 -->
    <list>
      <bean class="com.mvc.convertor.MyConvertor" />
    </list>
  </property>
</bean> 

@RequestMapping("convert")
public String convert(User user){
  System.out.println(user);
  return "model1";
}

public class MySuperConvertor implements Converter<String, SuperUser>{

  @Override
  public SuperUser convert(String source) {
    String[] values = source.split(",");
    Integer id = Integer.valueOf(values[0]);
    SuperUser superUser = new SuperUser(values[3], new User(id,values[1],values[2]));
    return superUser;
  }
}
/**********下面是SuperUser POJO類*********/
package com.mvc.model;

public class SuperUser extends User {
  private String name;
  //忽略get和set方法

  public SuperUser(String name,User user) {
    super(user.getId(),user.getUserName(),user.getPassword());
    this.name = name;
  }

  public SuperUser() {
    super();
  }

  @Override
  public String toString() {
    return "SuperUser [name=" + name + ", toString()=" + super.toString()
        + "]";
  }
}

public class MyConvertorFactory implements ConverterFactory<String, User>{

  @Override
  //T類型必須是User或其子類，Stirng是我們的轉(zhuǎn)換源類
  public <T extends User> Converter<String, T> getConverter(

      Class<T> targetType) {
    if(targetType == User.class){
      return (Converter<String, T>) new MyConvertor();
    }else{
      return (Converter<String, T>) new MySuperConvertor();
    }
  }
}

<!-- 通過:annotation-driven的conversion-service屬性來裝配我們的類型轉(zhuǎn)換器 -->
<mvc:annotation-driven conversion-service="factoryBean" />
<!-- 通過ConversionServiceFactoryBean注冊我們的自定義轉(zhuǎn)換器 -->
<bean class="org.springframework.context.support.ConversionServiceFactoryBean" id="factoryBean" >
  <property name="converters"><!-- 在屬性converters注冊 -->
    <list>
      <!--這里只要注冊我們自定義的轉(zhuǎn)換器工廠即可-->
      <bean class="com.mvc.convertor.MyConvertorFactory" />
    </list>
  </property>
</bean> 

//這是原來的
@RequestMapping("convert")
public String convert( User user){
  System.out.println(user);
  return "model1";
}
//下面是新添加的方法
@RequestMapping("convertSuper")
public String convert( SuperUser user){
  System.out.println(user);
  return "model1";
}