Jackson JSON框架的Util化封装

package net.csdn.blog.chaijunkun.util; import java.io.IOException; import java.io.StringWriter; import org.apache.log4j.Logger; import org.codehaus.jackson.JsonGenerationException; import org.codehaus.jackson.JsonGenerator; import org.codehaus.jackson.JsonParseException; import org.codehaus.jackson.JsonParser; import org.codehaus.jackson.map.JsonMappingException; import org.codehaus.jackson.map.ObjectMapper; import org.codehaus.jackson.map.SerializationConfig; import org.codehaus.jackson.map.ser.CustomSerializerFactory; public class JSONUtil { private static Logger logger= Logger.getLogger(JSONUtil.class); private static ObjectMapper objectMapper; /** * 懒惰单例模式得到ObjectMapper实例 * 此对象为Jackson的核心 */ private static ObjectMapper getMapper(){ if (objectMapper== null){ objectMapper= new ObjectMapper(); //当找不到对应的序列化器时 忽略此字段 objectMapper.configure(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS, false); //使Jackson JSON支持Unicode编码非ASCII字符 CustomSerializerFactory serializerFactory= new CustomSerializerFactory(); serializerFactory.addSpecificMapping(String.class, new StringUnicodeSerializer()); objectMapper.setSerializerFactory(serializerFactory); //支持结束 } return objectMapper; } /** * 创建JSON处理器的静态方法 * @param content JSON字符串 * @return */ private static JsonParser getParser(String content){ try{ return getMapper().getJsonFactory().createJsonParser(content); }catch (IOException ioe){ return null; } } /** * 创建JSON生成器的静态方法, 使用标准输出 * @return */ private static JsonGenerator getGenerator(StringWriter sw){ try{ return getMapper().getJsonFactory().createJsonGenerator(sw); }catch (IOException e) { return null; } } /** * JSON对象序列化 */ public static String toJSON(Object obj){ StringWriter sw= new StringWriter(); JsonGenerator jsonGen= getGenerator(sw); if (jsonGen== null){ try { sw.close(); } catch (IOException e) { } return null; } try { //由于在getGenerator方法中指定了OutputStream为sw //因此调用writeObject会将数据输出到sw jsonGen.writeObject(obj); //由于采用流式输出 在输出完毕后务必清空缓冲区并关闭输出流 jsonGen.flush(); jsonGen.close(); return sw.toString(); } catch (JsonGenerationException jge) { logger.error("JSON生成错误" + jge.getMessage()); } catch (IOException ioe) { logger.error("JSON输入输出错误" + ioe.getMessage()); } return null; } /** * JSON对象反序列化 */ public static <T> T fromJSON(String json, Class<T> clazz) { try { JsonParser jp= getParser(json); return jp.readValueAs(clazz); } catch (JsonParseException jpe){ logger.error(String.format("反序列化失败, 错误原因:%s", jpe.getMessage())); } catch (JsonMappingException jme){ logger.error(String.format("反序列化失败, 错误原因:%s", jme.getMessage())); } catch (IOException ioe){ logger.error(String.format("反序列化失败, 错误原因:%s", ioe.getMessage())); } return null; } }