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json格式转换
json数据转换
import java.io.IOException;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import org.apache.commons.lang3.StringUtils;
import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.JsonGenerator;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.DeserializationConfig.Feature;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.type.TypeReference;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
public class JsonParse {
/**
* 转换成json数据
*
* @param obj
* @return
*/
public static String getJson(Object obj) {
if (obj == null)
return null;
ObjectMapper om = new ObjectMapper();
StringWriter sw = new StringWriter();
try {
JsonGenerator jg = new JsonFactory().createJsonGenerator(sw);
om.writeValue(jg, obj);
jg.close();
} catch (IOException e) {
e.printStackTrace();
}
return sw.toString();
}
/**
* 将json数据转换成List<Object>
*
* @param json
* @param entityClass
* @return
*/
public static <T> List<T> getList(String json, Class<T> entityClass) {
if (StringUtils.isBlank(json))
return null;
List<T> list = new ArrayList<T>();
ObjectMapper om = new ObjectMapper();
om.configure(Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
try {
JSONArray array = new JSONArray(json);
for (int i = 0; i < array.length(); i++) {
T t = om.readValue(array.getString(i), entityClass);
list.add(t);
}
return list;
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* 将json数据转换成List<LinkedHashMap<String, Object>>
*
* @param json
* @return
*/
@SuppressWarnings("unchecked")
public static List<LinkedHashMap<String, Object>> getListMap(String json) {
if (StringUtils.isBlank(json))
return null;
ObjectMapper om = new ObjectMapper();
om.configure(Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
try {
List<LinkedHashMap<String, Object>> list = om.readValue(json, List.class);
return list;
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
/**
* 将json数据转换成List<Map<String, T>>
*
* @param json
* @return
*/
public static <T> List<Map<String, T>> getListMap(String json, Class<T> entityClass) {
if (StringUtils.isBlank(json))
return null;
ObjectMapper om = new ObjectMapper();
om.configure(Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
try {
List<Map<String, T>> list = om.readValue(json, new TypeReference<List<Map<String, T>>>() {
});
return list;
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
/**
* 将json数据转换成Map<String, Object>
*
* @param json
* @return
*/
@SuppressWarnings("unchecked")
public static Map<String, Object> getMap(String json) {
if (StringUtils.isBlank(json))
return null;
ObjectMapper om = new ObjectMapper();
om.configure(Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
try {
Map<String, Object> map = om.readValue(json, Map.class);
return map;
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
/**
* 将json数据转换成Map<String, T>
*
* @param json
* @return
*/
public static <T> Map<String, T> getMap(String json, Class<T> entityClass) {
if (StringUtils.isBlank(json))
return null;
ObjectMapper om = new ObjectMapper();
om.configure(Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
try {
Map<String, T> list = om.readValue(json, new TypeReference<Map<String, T>>() {
});
return list;
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
/**
* 将json数据转换成指定的类型
*
* @param json
* @param valueType
* @return
*/
public static <T> T getObject(String json, Class<T> valueType) {
if (StringUtils.isBlank(json))
return null;
ObjectMapper om = new ObjectMapper();
om.configure(Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
try {
return om.readValue(json, valueType);
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}
在BaseControl中可以写一个这样的方法
/**
* 输出HTML脚本
*/
protected void writeJson(HttpServletResponse response, Object obj) {
this.writeJson(response, obj, "utf-8");
}
/**
* 输出HTML脚本带格式
*/
protected void writeJson(HttpServletResponse response, Object obj, String charset) {
String json = JsonParse.getJson(obj);
response.setContentType("text/html;charset=" + charset);
response.setDateHeader("Expires", -10);
PrintWriter out = null;
try {
out = response.getWriter();
out.println(json);
out.flush();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (out != null)
out.close();
}
}
在使用时，继承BaseControl，调用writeJson方法，返回给前台的是json格式的字符串。
this.writeJson(response, helloService.getSomething(id));
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