sdk-java/README.md

1. 通过HTTP协议用：
直接拼接URL参考：https://public.internetapi.cn/docs/bdcontract/doc/ContractAPI.html#id69

使用SDK参考test目录下的SmartContractHttpClientTest.java
```java
//当需要发起签名调用时，使用正确的privateKey和publicKey。
SmartContractHttpClient client =
                new SmartContractHttpClient(
                        SM2KeyPair.fromJson(
                                "{\"privateKey\":\"...\",\"publicKey\":\"...\"}"),
                        IP,
                        port);
        System.out.println(client.executeContractAsString(contractID_or_contractName, operation,arg));
```

2.通过WebSocket调用
使用SDK参考test目录下的SmartClientTest.java
```java
SmartContractClient client = new SmartContractClient("ws://ip:port/SCIDE/SCExecutor") ;
//如果需要指定key，也可传入key参数。
//SM2KeyPair key =    SM2KeyPair.fromJson("json格式的密钥对");
//client = new SmartContractClient("...",key);
client.waitForConnect();
client.login();
ContractRequest cr = new ContractRequest();
cr.setContractID("xxx");
cr.setAction("xxx");
cr.setArg("xxx");
JsonObject result = testClient.executeContractSync(cr);
```