JAVA实现json和对象间的相互转换，支持复杂对象格式

jackson-core-asl-1.9.12.jar

jackson-mapper-asl-1.9.12.jar

package com.psd.test;import java.io.IOException;import java.text.SimpleDateFormat;import java.util.List;import org.apache.commons.lang3.StringUtils;import org.codehaus.jackson.JsonNode;import org.codehaus.jackson.JsonProcessingException;import org.codehaus.jackson.map.DeserializationConfig;import org.codehaus.jackson.map.ObjectMapper;import org.codehaus.jackson.map.SerializationConfig;import org.codehaus.jackson.map.annotate.JsonSerialize.Inclusion;import org.codehaus.jackson.map.util.JSONPObject;import org.codehaus.jackson.type.JavaType;import org.slf4j.Logger;import org.slf4j.LoggerFactory;/** * 简单封装Jackson，实现JSON String<->Java Object的Mapper. *  * 封装不同的输出风格, 使用不同的builder函数创建实例. *  */public class JsonMapper {  private static Logger logger = LoggerFactory.getLogger(JsonMapper.class);  private ObjectMapper mapper;  public JsonMapper(Inclusion inclusion) {    mapper = new ObjectMapper();    //设置输出时包含属性的风格    mapper.setSerializationInclusion(inclusion);    //设置输入时忽略在JSON字符串中存在但Java对象实际没有的属性    mapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);    //禁止使用int代表Enum的order()來反序列化Enum,非常危險    mapper.configure(DeserializationConfig.Feature.FAIL_ON_NUMBERS_FOR_ENUMS, true);  }  /**   * 创建输出全部属性到Json字符串的Mapper.   */  public static JsonMapper buildNormalMapper() {    return new JsonMapper(Inclusion.ALWAYS);  }  /**   * 创建只输出非空属性到Json字符串的Mapper.   */  public static JsonMapper buildNonNullMapper() {    return new JsonMapper(Inclusion.NON_NULL);  }  /**   * 创建只输出初始值被改变的属性到Json字符串的Mapper.   */  public static JsonMapper buildNonDefaultMapper() {    return new JsonMapper(Inclusion.NON_DEFAULT);  }  /**   * 创建只输出非Null且非Empty(如List.isEmpty)的属性到Json字符串的Mapper.   */  public static JsonMapper buildNonEmptyMapper() {    return new JsonMapper(Inclusion.NON_EMPTY);  }  /**   * 如果对象为Null, 返回"null".   * 如果集合为空集合, 返回"[]".   */  public String toJson(Object object) {    try {      return mapper.writeValueAsString(object);    } catch (IOException e) {      throw NestedException.wrap(e);    }  }  /**   * 如果JSON字符串为Null或"null"字符串, 返回Null.   * 如果JSON字符串为"[]", 返回空集合.   *    * 如需读取集合如List/Map, 且不是List<String>这种简单类型时,先使用函數constructParametricType构造类型.   * @see #constructParametricType(Class, Class...)   */  public <T> T fromJson(String jsonString, Class<T> clazz) {    if (StringUtils.isEmpty(jsonString)) {      return null;    }    try {      return mapper.readValue(jsonString, clazz);    } catch (IOException e) {      throw NestedException.wrap(e);    }  }  /**   * 如果JSON字符串为Null或"null"字符串, 返回Null.   * 如果JSON字符串为"[]", 返回空集合.   *    * 如需读取集合如List/Map, 且不是List<String>这种简单类型时,先使用函數constructParametricType构造类型.   * @see #constructParametricType(Class, Class...)   */  @SuppressWarnings("unchecked")  public <T> T fromJson(String jsonString, JavaType javaType) {    if (StringUtils.isEmpty(jsonString)) {      return null;    }    try {      return (T) mapper.readValue(jsonString, javaType);    } catch (IOException e) {      throw NestedException.wrap(e);    }  }    @SuppressWarnings("unchecked")  public <T> T fromJson(String jsonString, Class<?> parametrized, Class<?>... parameterClasses) {    return (T) this.fromJson(jsonString, constructParametricType(parametrized, parameterClasses));  }    @SuppressWarnings("unchecked")  public <T> List<T> fromJsonToList(String jsonString, Class<T> classMeta){    return (List<T>) this.fromJson(jsonString,constructParametricType(List.class, classMeta));  }    @SuppressWarnings("unchecked")  public <T> T fromJson(JsonNode node, Class<?> parametrized, Class<?>... parameterClasses) {    JavaType javaType = constructParametricType(parametrized, parameterClasses);    try {      return (T) mapper.readValue(node, javaType);    } catch (IOException e) {      throw NestedException.wrap(e);    }  }    @SuppressWarnings("unchecked")  public <T> T pathAtRoot(String json, String path, Class<?> parametrized, Class<?>... parameterClasses){    JsonNode rootNode = parseNode(json);    JsonNode node = rootNode.path(path);    return (T) fromJson(node, parametrized, parameterClasses);  }    @SuppressWarnings("unchecked")  public <T> T pathAtRoot(String json, String path, Class<T> clazz){    JsonNode rootNode = parseNode(json);    JsonNode node = rootNode.path(path);    return (T) fromJson(node, clazz);  }  /**   * 構造泛型的Type如List<MyBean>, 则调用constructParametricType(ArrayList.class,MyBean.class)   *             Map<String,MyBean>则调用(HashMap.class,String.class, MyBean.class)   */  public JavaType constructParametricType(Class<?> parametrized, Class<?>... parameterClasses) {    return mapper.getTypeFactory().constructParametricType(parametrized, parameterClasses);  }  /**   * 當JSON裡只含有Bean的部分屬性時，更新一個已存在Bean，只覆蓋該部分的屬性.   */  @SuppressWarnings("unchecked")  public <T> T update(T object, String jsonString) {    try {      return (T) mapper.readerForUpdating(object).readValue(jsonString);    } catch (JsonProcessingException e) {      logger.warn("update json string:" + jsonString + " to object:" + object + " error.", e);    } catch (IOException e) {      logger.warn("update json string:" + jsonString + " to object:" + object + " error.", e);    }    return null;  }  /**   * 輸出JSONP格式數據.   */  public String toJsonP(String functionName, Object object) {    return toJson(new JSONPObject(functionName, object));  }  /**   * 設定是否使用Enum的toString函數來讀寫Enum,   * 為False時時使用Enum的name()函數來讀寫Enum, 默認為False.   * 注意本函數一定要在Mapper創建後, 所有的讀寫動作之前調用.   */  public void setEnumUseToString(boolean value) {    mapper.configure(SerializationConfig.Feature.WRITE_ENUMS_USING_TO_STRING, value);    mapper.configure(DeserializationConfig.Feature.READ_ENUMS_USING_TO_STRING, value);  }  /**   * 取出Mapper做进一步的设置或使用其他序列化API.   */  public ObjectMapper getMapper() {    return mapper;  }    public JsonNode parseNode(String json){    try {      return mapper.readValue(json, JsonNode.class);    } catch (IOException e) {      throw NestedException.wrap(e);    }  }    /**   * 输出全部属性   * @param object   * @return   */  public static String toNormalJson(Object object){    return new JsonMapper(Inclusion.ALWAYS).toJson(object);  }    /**   * 输出非空属性   * @param object   * @return   */  public static String toNonNullJson(Object object){    return new JsonMapper(Inclusion.NON_NULL).toJson(object);  }    /**   * 输出初始值被改变部分的属性   * @param object   * @return   */  public static String toNonDefaultJson(Object object){    return new JsonMapper(Inclusion.NON_DEFAULT).toJson(object);  }    /**   * 输出非Null且非Empty(如List.isEmpty)的属性   * @param object   * @return   */  public static String toNonEmptyJson(Object object){    return new JsonMapper(Inclusion.NON_EMPTY).toJson(object);  }    public void setDateFormat(String dateFormat){    mapper.setDateFormat(new SimpleDateFormat(dateFormat));  }    public static String toLogJson(Object object){    JsonMapper jsonMapper = new JsonMapper(Inclusion.NON_EMPTY);    jsonMapper.setDateFormat("yyyy-MM-dd HH:mm:ss");    return jsonMapper.toJson(object);  }}

package com.ebiz.logic.service.impl;public class NestedException extends RuntimeException {  private static final long serialVersionUID = 5893258079497055346L;    private Throwable throwable;  private NestedException(Throwable t) {    this.throwable = t;  }  /** Wraps another exeception in a RuntimeException. */  public static RuntimeException wrap(Throwable t) {    if (t instanceof RuntimeException)      return (RuntimeException) t;    return new NestedException(t);  }  public Throwable getCause() {    return this.throwable;  }  public void printStackTrace() {    this.throwable.printStackTrace();  }}

package com.ebiz.uniservice.fightdata.test;import java.util.List;public class Student {  private String name;  private int age;  private List<Teacher> teachers;  public void setName(String name) {    this.name = name;  }  public String getName() {    return name;  }  public void setAge(int age) {    this.age = age;  }  public int getAge() {    return age;  }  public void setTeachers(List<Teacher> teachers) {    this.teachers = teachers;  }  public List<Teacher> getTeachers() {    return teachers;  }}

package com.ebiz.uniservice.fightdata.test;public class Teacher {  private String name;  private int age;  public Teacher() {      }    public Teacher(String name, int age) {    super();    this.name = name;    this.age = age;  }  public void setName(String name) {    this.name = name;  }  public String getName() {    return name;  }  public void setAge(int age) {    this.age = age;  }  public int getAge() {    return age;  }}

package com.ebiz.uniservice.fightdata.test;import java.util.ArrayList;import com.ebiz.logic.service.impl.JsonMapper;/** *  * @author jsqiu * */public class JsonTest {  public static void main(String[] args) {    Student student = getStudents();    Long beginTime = System.currentTimeMillis();    //bean2json    String json = JsonMapper.toLogJson(student);    System.out.println("对象转换为json：" + json);    System.out.println("转换用时：" + (System.currentTimeMillis()-beginTime) + "ms");    //json2bean，需要注意：Student类和Teacher类必须有一个空的构造方法    beginTime = System.currentTimeMillis();    //JsonMapper提供了很多创建Mapper的方法，不是非要用buildNonDefaultMapper，你可以对比几种方法的转换时间，挑个最快的    Student student2 = JsonMapper.buildNonDefaultMapper().fromJson(json, Student.class);    System.out.println("json转换成对象：" + student2);    System.out.println("转换用时：" + (System.currentTimeMillis()-beginTime) + "ms");  }  /**   * 初始化一个student   * @return   */  private static Student getStudents() {    Teacher t1 = new Teacher("teacher1",35);    Teacher t2 = new Teacher("teacher1",25);    Teacher t3 = new Teacher("teacher1",30);    ArrayList<Teacher> teachers = new ArrayList<Teacher>();    teachers.add(t1);    teachers.add(t2);    teachers.add(t3);    Student s = new Student();    s.setAge(20);    s.setName("student1");    s.setTeachers(teachers);    return s;  }}

对象转换为json：{"name":"student1","age":20,"teachers":[{"name":"teacher1","age":35},{"name":"teacher1","age":25},{"name":"teacher1","age":30}]}

json转换成对象：com.ebiz.uniservice.fightdata.test.Student@55e55f