<p>面对一些不规范的json,我们的gson解析经常会抛出各种异常导致app崩溃,这里可以采取一些措施来避免</p>    <h2><strong>Json异常情况</strong></h2>    <p>先来看一个后台返回的json</p>    <p>正常情况下json:</p>    <pre>  <code class="language-java">{      "code":0,      "msg":"ok",      "data":{          "id":5638,          "newsId":5638      }  }</code></pre>    <p>data部分对应的实体类:</p>    <pre>  <code class="language-java">public class JsonBean {      private int id;      private int newsId;        public int getId() {          return id;      }        public void setId(int id) {          this.id = id;      }        public int getNewsId() {          return newsId;      }        public void setNewsId(int newsId) {          this.newsId = newsId;      }  }</code></pre>    <p>异常情况json(后台数据库newsId字段未查询到对应数据):</p>    <pre>  <code class="language-java">{      "code":0,      "msg":"ok",      "data":{          "id":5638,          "newsId":""      }  }</code></pre>    <p>这样Gson在解析时就会抛出解析错误的异常,app崩溃,原因是无法将""转化为int</p>    <h2><strong>json异常的处理</strong></h2>    <p>我们期望在后台返回的json异常时,也能解析成功,空值对应的转换为默认值,如:newsId=0;</p>    <p>这里排除掉后台开发人员输出时给你做矫正,还是得靠自己啊---</p>    <p>我们写一个针对int值的类型转换器,需要实现Gson的 JsonSerializer<T> 接口和 JsonDeserializer<T> ,即序列化和反序列化接口</p>    <pre>  <code class="language-java">public class IntegerDefault0Adapter implements JsonSerializer<Integer>, JsonDeserializer<Integer> {      @Override      public Integer deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)              throws JsonParseException {          try {              if (json.getAsString().equals("") || json.getAsString().equals("null")) {//定义为int类型,如果后台返回""或者null,则返回0                  return 0;              }          } catch (Exception ignore) {          }          try {              return json.getAsInt();          } catch (NumberFormatException e) {              throw new JsonSyntaxException(e);          }      }        @Override      public JsonElement serialize(Integer src, Type typeOfSrc, JsonSerializationContext context) {          return new JsonPrimitive(src);      }  }</code></pre>    <h3><strong>同理Long及Double类型</strong></h3>    <p>double=></p>    <pre>  <code class="language-java">public class DoubleDefault0Adapter implements JsonSerializer<Double>, JsonDeserializer<Double> {      @Override      public Double deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {          try {              if (json.getAsString().equals("") || json.getAsString().equals("null")) {//定义为double类型,如果后台返回""或者null,则返回0.00                  return 0.00;          }              } catch (Exception ignore) {          }          try {              return json.getAsDouble();          } catch (NumberFormatException e) {              throw new JsonSyntaxException(e);          }      }        @Override      public JsonElement serialize(Double src, Type typeOfSrc, JsonSerializationContext context) {          return new JsonPrimitive(src);      }  }</code></pre>    <p>long=></p>    <pre>  <code class="language-java">public class LongDefault0Adapter implements JsonSerializer<Long>, JsonDeserializer<Long> {      @Override      public Long deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)          throws JsonParseException {          try {              if (json.getAsString().equals("") || json.getAsString().equals("null")) {//定义为long类型,如果后台返回""或者null,则返回0                      return 0l;                  }              } catch (Exception ignore) {          }          try {              return json.getAsLong();          } catch (NumberFormatException e) {              throw new JsonSyntaxException(e);          }      }        @Override      public JsonElement serialize(Long src, Type typeOfSrc, JsonSerializationContext context) {          return new JsonPrimitive(src);      }  }</code></pre>    <p>所以使用是这样的:</p>    <pre>  <code class="language-java">return new Retrofit.Builder()         .client(okHttpClient)//设置网络访问框架         .addConverterFactory(GsonConverterFactory.create(buildGson()))//添加json转换框架         .addCallAdapterFactory(RxJavaCallAdapterFactory.create())//让Retrofit支持RxJava         .baseUrl(baseUrl)         .build();    /**   * 增加后台返回""和"null"的处理   * 1.int=>0   * 2.double=>0.00   * 3.long=>0L   *   * @return   */  public static Gson buildGson() {      if (gson == null) {          gson = new GsonBuilder()                  .registerTypeAdapter(Integer.class, new IntegerDefault0Adapter())                  .registerTypeAdapter(int.class, new IntegerDefault0Adapter())                  .registerTypeAdapter(Double.class, new DoubleDefault0Adapter())                  .registerTypeAdapter(double.class, new DoubleDefault0Adapter())                  .registerTypeAdapter(Long.class, new LongDefault0Adapter())                  .registerTypeAdapter(long.class, new LongDefault0Adapter())                  .create();      }      return gson;  }</code></pre>    <p>再也不会因为后台json字段为空的情况崩溃了</p>    <p> </p>    <p> </p>    <p>来自：http://www.jianshu.com/p/e03a96f5a321</p>    <p> </p>