Java 之利用OkHttpClient进行简单的http请求，利用Jackson框架把json转化为java对象的实现

最新推荐文章于 2025-07-27 13:28:01 发布

转载最新推荐文章于 2025-07-27 13:28:01 发布 · 890 阅读

本文详细介绍了如何使用OkHttp进行HTTP请求，并利用Jackson库将JSON响应转换为Java对象。通过具体示例，展示了如何处理GET和POST请求，以及如何定义JavaBean来简化JSON与Java类之间的转换。

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实现的业务逻辑是这样的：
通过http请求，返回一个json格式的数据，然后将json数据转化为java对象返回给调用方。
Http采用OkHttp库，json转化采用jackson库。
一.简介
1）okhttpclient
OkHttpClient官网： http://square.github.io/okhttp/
OkHttp GitHub地址：https://github.com/square/okhttp
最常用的是两个http请求是get和post，我下面的代码就只用到这两个请求。
Maven依赖：
<dependency>
<groupId>com.squareup.okhttp3</groupId>
<artifactId>okhttp</artifactId>
<version>3.6.0</version>
</dependency>
2）jackson
Jackson的文档：http://wiki.fasterxml.com/JacksonInFiveMinutes
Jackson的maven依赖
<dependency>
<groupId>com.fasterxml.jackson</groupId>
<artifactId>jackson-parent</artifactId>
<version>2.8</version>
</dependency>
由于采用了javabean的方式，所以json和java类的互转变得简单。

二．代码

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java类：

public class Transaction {

　　//使用了静态的内部类

public static class Output{

String address;

long amount;

public String getAddress() {

return address;

}

public long getAmount() {

return amount;

}

public void setAddress(String address) {

this.address = address;

}

public void setAmount(long amount) {

this.amount = amount;

}

@Override

public String toString() {

return "Output{" +

"address='" + address + '\'' +

", amount=" + amount +

'}';

}

private String txid;

private String action;

private long amount;

private long fees;

private long time;

private int confirmations;

private List<Output> outputs;

public void setTxid(String txid) {

this.txid = txid;

}

public void setAction(String action) {

this.action = action;

}

public void setAmount(long amount) {

this.amount = amount;

}

public void setFees(long fees) {

this.fees = fees;

}

public void setTime(long time) {

this.time = time;

}

public void setConfirmations(int confirmations) {

this.confirmations = confirmations;

}

public String getTxid() {

return txid;

}

public void setOutputs(List<Output> outputs) {

this.outputs = outputs;

}

@Override

public String toString() {

return "Transaction{" +

"txid='" + txid + '\'' +

", action='" + action + '\'' +

", amount=" + amount +

", fees=" + fees +

", time=" + time +

", confirmations=" + confirmations +

", outputs=" + outputs +

'}';

}

http请求：

public class HttpClient {

public static final MediaType JSON = MediaType.parse("application/json;charset=utf-8");

public static String httpGet(String url) throws IOException {

OkHttpClient httpClient = new OkHttpClient();

Request request = new Request.Builder()

.url(url)

.build();

Response response = httpClient.newCall(request).execute();

return response.body().string(); // 返回的是string 类型，json的mapper可以直接处理

}

public static String httpPost(String url, String json) throws IOException {

OkHttpClient httpClient = new OkHttpClient();

RequestBody requestBody = RequestBody.create(JSON, json);

Request request = new Request.Builder()

.url(url)

.post(requestBody)

.build();

Response response = httpClient.newCall(request).execute();

return response.body().string();

}

｝

json转化：

public Transaction[] getTransaction(int skip,int limit){

String txHistoryUrl = String.format("%s%s?skip=%d&limit=%d",url,TX_HISTORY,skip,limit); //url 后边的参数是业务规定，格式可以参考，具体可以自定义

System.out.println(txHistoryUrl);

try{

String newTx = HttpClient.httpGet(txHistoryUrl);

System.out.println(newTx);

ObjectMapper mapper = new ObjectMapper(); // 只需要一个mapper就可以实现

return mapper.readValue(newTx,Transaction[].class);

}catch (IOException e){

e.printStackTrace();

}

return null;

}

json数据如下：
[{"txid":"ad416e1b4b8b807b4a0946affb17cf253c1af7a7e6c6a9e21fac2e93b2c88746","action":"received","amount":10000,"fees":3800,"time":1486111663,"confirmations":179,"outputs":[{"amount":10000,"address":"2MxDyD4idPv8LqYNP4Aq4QExRhTckqNK8zK"}]},{"txid":"2dadf7b391935af15f5f70e775ed5d7a03d629db4bdde1cd93e31b8311db4949","action":"received","amount":1000000,"fees":4416,"time":1485241194,"confirmations":1721,"outputs":[{"amount":1000000,"address":"2MxDyD4idPv8LqYNP4Aq4QExRhTckqNK8zK"}]}]

三．问题解决
Json错误：Can not deserialize instance of xx out of START_ARRAY token
Server
这个可能是后台返回的是数组类型的json，所以transaction要用数组
return mapper.readValue(newTx,Transaction[].class);
json错误：
No suitable constructor found for type [xxxx]: can not instantiate from JSON object (need to add/enable type information?) at xxx
这个需要java class中的内部类使用静态类，见transaction类中的output内部类。

后续复杂应用，再接着写。