Fastjson解析json时遇到问题之后——

今天，2015年10月29日。

在运行eclipse时，遇到如下问题：

 com.alibaba.fastjson.JSONException: syntax error, expect {, actual error, pos 0
 at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.deserialze(JavaBeanDeserializer.java:212)
 at com.alibaba.fastjson.parser.deserializer.ASMJavaBeanDeserializer.parseRest(ASMJavaBeanDeserializer.java:96)
 at Fastjson_ASM_UpdateRequest_1.deserialze(Unknown Source)
 at com.alibaba.fastjson.parser.DefaultJSONParser.parseObject(DefaultJSONParser.java:513)
 at com.alibaba.fastjson.JSON.parseObject(JSON.java:244)
 at com.alibaba.fastjson.JSON.parseObject(JSON.java:220)
 at com.alibaba.fastjson.JSON.parseObject(JSON.java:179)
 at com.alibaba.fastjson.JSON.parseObject(JSON.java:327)

看到这个，第一反应是解析的json格式不对，遂详细排查json格式问题。无奈怎么也找不到原因，在网上也没有找到解决方案。后无意间发现，原来是http请求方式错误。Get请求写成了Post请求。因此记录下这次的错误，以后不要再犯。

另附http请求之POSTandGET。

• POST篇：

private static Token getRemoteAccessToken() {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpPost httppost = new HttpPost(URL);
        httppost.setHeader("Content-Type", ContentType);
        List<NameValuePair> params = new ArrayList<>();
        params.add(new BasicNameValuePair("grant_type", GrantTypeCredentials));
        params.add(new BasicNameValuePair("client_id", ClientId));
        params.add(new BasicNameValuePair("client_secret", ClientSecret));
        params.add(new BasicNameValuePair("scope", Scope));
        UrlEncodedFormEntity urlEncodedFormEntity = new UrlEncodedFormEntity(params, Charset.forName("UTF-8"));
        
        // 获取Token。
        Token token = null;
        httppost.setEntity(urlEncodedFormEntity);
        // 发送
        try (CloseableHttpResponse httpResponse = httpClient.execute(httppost)) {
            HttpEntity entity = httpResponse.getEntity();
            if (entity != null) {
                String entityString = EntityUtils.toString(entity, Charset.forName("UTF-8"));
                token = JSON.parseObject(entityString, Token.class);
            }
        } catch (IOException e) {
            LOGGER.error(ExceptionUtils.parseExceptionStackTrace(e));
        } finally {
            try {
                httpClient.close();
            } catch (IOException e) {
                LOGGER.error(ExceptionUtils.parseExceptionStackTrace(e));
            }
        }
        return token;
    }

• GET篇：

public Double getValue(String from,String to,Double value,String url) {
        StringBuilder sbUri = new StringBuilder(url);
        sbUri.append("?");
        sbUri.append("from=");sbUri.append(from);
        sbUri.append("&");
        sbUri.append("to=");sbUri.append(to);
        sbUri.append("&");
        sbUri.append("value=");sbUri.append(value.toString());
        
        //获取转换后value
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpGet httpGet = new HttpGet(sbUri.toString()); 
        httpGet.setHeader("Content-Type", ContentType);
        
        UnitValue unitValue = null;        
        try (CloseableHttpResponse httpResponse = httpClient.execute(httpGet)) {        
            HttpEntity entity = httpResponse.getEntity();
            if (entity != null) {
                String entityString = EntityUtils.toString(entity, Charset.forName("UTF-8"));
                unitValue = JSON.parseObject(entityString, UnitValue.class);            
                value=unitValue.getValue();
            }
        } catch (IOException e) {
            LOGGER.error(ExceptionUtils.parseExceptionStackTrace(e));
        } finally {
            try {
                httpClient.close();
            } catch (IOException e) {
                LOGGER.error(ExceptionUtils.parseExceptionStackTrace(e));
            }
        }
        return value;
    }