今天同事问我个问题。她需要把字符串的json转换成实体类，但是一直报错。主要是实体类当中的内部类需要用静态字段static修饰，否则无法访问。
以下是报错信息
org.codehaus.jackson.map.JsonMappingException: No suitable constructor found for type [simple type, class com.macxen.speechrecognition.JsonRootBean$Result]: can not instantiate from JSON object (need to add/enable type information?)at [Source: java.io.StringReader@3db5162; line: 1, column: 100] (through reference chain: com.macxen.speechrecognition.JsonRootBean["origin_result"]->com.macxen.speechrecognition.Origin_result["result"])
1.首先导入marven
<dependency><groupId>org.codehaus.jackson</groupId><artifactId>jackson-mapper-lgpl</artifactId><version>1.9.13</version><scope>test</scope></dependency>
2.jackonMapper
package com.sunian.besjon;import org.codehaus.jackson.map.ObjectMapper;/*** @author sunian* @name speechRecognition* @class name：com.sunian.speechrecognition.util* @time /11/7 10:14* @describe describe*/public class JacksonMapper {private static final ObjectMapper mapper = new ObjectMapper();private JacksonMapper() {}public static ObjectMapper getInstance() {return mapper;}}
3.JsonRootBean
package com.macxen.besjon;import java.io.Serializable;import java.util.List;/*** @author lainuo* @name speechRecognition* @class name：com.macxen.speechrecognition* @time /11/6 19:30* @describe 实体类*/public class JsonRootBean implements Serializable {private String result_type;private String best_result;private List<String> results_recognition;private Origin_result origin_result;private int error;public JsonRootBean() {}public void setResult_type(String result_type) {this.result_type = result_type;}public String getResult_type() {return result_type;}public void setBest_result(String best_result) {this.best_result = best_result;}public String getBest_result() {return best_result;}public void setResults_recognition(List<String> results_recognition) {this.results_recognition = results_recognition;}public List<String> getResults_recognition() {return results_recognition;}public void setOrigin_result(Origin_result origin_result) {this.origin_result = origin_result;}public Origin_result getOrigin_result() {return origin_result;}public void setError(int error) {this.error = error;}public int getError() {return error;}public static class Result implements Serializable {private List<String> word;public Result() {}public void setWord(List<String> word) {this.word = word;}public List<String> getWord() {return word;}}public static class Origin_result implements Serializable {private Result result;private String sn;private int err_no;private long corpus_no;private double voice_energy;public Origin_result() {}public void setResult(Result result) {this.result = result;}public Result getResult() {return result;}public void setSn(String sn) {this.sn = sn;}public String getSn() {return sn;}public void setErr_no(int err_no) {this.err_no = err_no;}public int getErr_no() {return err_no;}public void setCorpus_no(long corpus_no) {this.corpus_no = corpus_no;}public long getCorpus_no() {return corpus_no;}public void setVoice_energy(double voice_energy) {this.voice_energy = voice_energy;}public double getVoice_energy() {return voice_energy;}}}
4.JsonUtil
package com.sunian.besjon;import org.codehaus.jackson.map.ObjectMapper;/*** @author sunian* @name speechRecognition* @class name：com.sunian.speechrecognition.util* @time /11/7 10:15* @describe describe*/public class JsonUtil {public static String getJsonString(Object object) throws Exception {return JacksonMapper.getInstance().writeValueAsString(object);}public static Object toObject(String jsonString, Class cls) throws Exception {ObjectMapper objectMapper = new ObjectMapper();return objectMapper.readValue(jsonString, cls);}}
5.执行测试类
String json = "{\n" +"\t\"results_recognition\": [\"沧州。\"],\n" +"\t\"origin_result\": {\n" +"\t\t\"corpus_no\": 6621008601394242097,\n" +"\t\t\"err_no\": 0,\n" +"\t\t\"result\": {\n" +"\t\t\t\"word\": [\"沧州。\"]\n" +"\t\t},\n" +"\t\t\"sn\": \"fbc63952-92f7-49cd-b044-5204afd7ba01_s-79\",\n" +"\t\t\"voice_energy\": 12175.6875\n" +"\t},\n" +"\t\"error\": 0,\n" +"\t\"best_result\": \"沧州。\",\n" +"\t\"result_type\": \"final_result\"\n" +"}";@Testpublic void getJsonRootBean() throws Exception {Object o = JsonUtil.toObject(json, JsonRootBean.class);System.out.println(o);}
6.将json转换成实体类
