Java实现操作JSON的便捷工具类完整实例

本文实例讲述了Java实现操作JSON的便捷工具类。分享给大家供大家参考，具体如下：

对于JSON数据格式的处理，自开发Java以来，已用过多种JSON的开源工具，用得最好，也用得最High的恐怕要属Google的Gson了。

特别为它写了一个工具类，放入常备工具中，方便使用。下面是为GSON 1.5版本重写的工具类。

依赖包：

slf4j-api-1.6.0.jar
slf4j-log4j12-1.6.0.jar
log4j-1.2.15.jar
gson-1.5.jar

package my.tools;
import java.lang.reflect.Type;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.reflect.TypeToken;
import org.apache.commons.lang.StringUtils;

public class JSonUtils {
  private static final Logger LOGGER = LoggerFactory.getLogger(JSONUtils.class);
  
  public static final String EMPTY_JSON = "{}";
  
  public static final String EMPTY_JSON_ARRAY = "[]";
  
  public static final String DEFAULT_DATE_PATTERN = "yyyy-MM-dd HH:mm:ss SSS";
  
  public static final double SINCE_VERSION_10 = 1.0d;
  
  public static final double SINCE_VERSION_11 = 1.1d;
  
  public static final double SINCE_VERSION_12 = 1.2d;
  
  public static final double UNTIL_VERSION_10 = SINCE_VERSION_10;
  
  public static final double UNTIL_VERSION_11 = SINCE_VERSION_11;
  
  public static final double UNTIL_VERSION_12 = SINCE_VERSION_12;
  
  public JSonUtils() {
    super();
  }
  
  public static String toJson(Object target, Type targetType, boolean isSerializeNulls, Double version,
      String datePattern, boolean excludesFieldsWithoutExpose) {
    if (target == null) return EMPTY_JSON;
    GsonBuilder builder = new GsonBuilder();
    if (isSerializeNulls) builder.serializeNulls();
    if (version != null) builder.setVersion(version.doublevalue());
    if (StringUtils.isBlank(datePattern)) datePattern = DEFAULT_DATE_PATTERN;
    builder.setDateFormat(datePattern);
    if (excludesFieldsWithoutExpose) builder.excludeFieldsWithoutExposeAnnotation();
    return toJson(target, targetType, builder);
  }
  
  public static String toJson(Object target) {
    return toJson(target, null, false, null, null, true);
  }
  
  public static String toJson(Object target, String datePattern) {
    return toJson(target, null, false, null, datePattern, true);
  }
  
  public static String toJson(Object target, Double version) {
    return toJson(target, null, false, version, null, true);
  }
  
  public static String toJson(Object target, boolean excludesFieldsWithoutExpose) {
    return toJson(target, null, false, null, null, excludesFieldsWithoutExpose);
  }
  
  public static String toJson(Object target, Double version, boolean excludesFieldsWithoutExpose) {
    return toJson(target, null, false, version, null, excludesFieldsWithoutExpose);
  }
  
  public static String toJson(Object target, Type targetType) {
    return toJson(target, targetType, false, null, null, true);
  }
  
  public static String toJson(Object target, Type targetType, Double version) {
    return toJson(target, targetType, false, version, null, true);
  }
  
  public static String toJson(Object target, Type targetType, boolean excludesFieldsWithoutExpose) {
    return toJson(target, targetType, false, null, null, excludesFieldsWithoutExpose);
  }
  
  public static String toJson(Object target, Type targetType, Double version, boolean excludesFieldsWithoutExpose) {
    return toJson(target, targetType, false, version, null, excludesFieldsWithoutExpose);
  }
  
  public static  T fromJson(String json, TypeToken token, String datePattern) {
    if (StringUtils.isBlank(json)) {
      return null;
    }
    GsonBuilder builder = new GsonBuilder();
    if (StringUtils.isBlank(datePattern)) {
      datePattern = DEFAULT_DATE_PATTERN;
    }
    Gson gson = builder.create();
    try {
      return gson.fromJson(json, token.getType());
    } catch (Exception ex) {
      LOGGER.error(json + " 无法转换为 " + token.getRawType().getName() + " 对象!", ex);
      return null;
    }
  }
  
  public static  T fromJson(String json, TypeToken token) {
    return fromJson(json, token, null);
  }
  
  public static  T fromJson(String json, Class clazz, String datePattern) {
    if (StringUtils.isBlank(json)) {
      return null;
    }
    GsonBuilder builder = new GsonBuilder();
    if (StringUtils.isBlank(datePattern)) {
      datePattern = DEFAULT_DATE_PATTERN;
    }
    Gson gson = builder.create();
    try {
      return gson.fromJson(json, clazz);
    } catch (Exception ex) {
      LOGGER.error(json + " 无法转换为 " + clazz.getName() + " 对象!", ex);
      return null;
    }
  }
  
  public static  T fromJson(String json, Class clazz) {
    return fromJson(json, clazz, null);
  }
  
  public static String toJson(Object target, Type targetType, GsonBuilder builder) {
    if (target == null) return EMPTY_JSON;
    Gson gson = null;
    if (builder == null) {
      gson = new Gson();
    } else {
      gson = builder.create();
    }
    String result = EMPTY_JSON;
    try {
      if (targetType == null) {
 result = gson.toJson(target);
      } else {
 result = gson.toJson(target, targetType);
      }
    } catch (Exception ex) {
      LOGGER.warn("目标对象 " + target.getClass().getName() + " 转换 JSON 字符串时，发生异常！", ex);
      if (target instanceof Collection || target instanceof Iterator || target instanceof Enumeration
   || target.getClass().isArray()) {
 result = EMPTY_JSON_ARRAY;
      }
    }
    return result;
  }
}

PS：关于json操作，这里再为大家推荐几款比较实用的json在线工具供大家参考使用：

在线JSON代码检验、检验、美化、格式化工具：
http://tools.jb51.net/code/json

JSON在线格式化工具：
http://tools.jb51.net/code/jsonformat

在线XML/JSON互相转换工具：
http://tools.jb51.net/code/xmljson

json代码在线格式化/美化/压缩/编辑/转换工具：
http://tools.jb51.net/code/jsoncodeformat

在线json压缩/转义工具：
http://tools.jb51.net/code/json_yasuo_trans

更多关于java相关内容感兴趣的读者可查看本站专题：《Java操作json格式数据技巧总结》、《Java数组操作技巧总结》、《Java字符与字符串操作技巧总结》、《Java数学运算技巧总结》、《Java数据结构与算法教程》及《Java操作DOM节点技巧总结》

希望本文所述对大家java程序设计有所帮助。