記錄一下APP怎麼通過以太坊的RPC介面實現遠端呼叫。此過程的環境為Window7和Android studio2.2.3。以web3_clientVersion為例。更多用法參考Geth JSON-RPC和Management APIs。首先啟動geth私有鏈並設定RPC埠

geth --identity “blossom” --rpc --rpccorsdomain “*” --datadir “%cd%” --port “30303” --rpcapi “personal,db,eth,net,web3,miner” --networkid 66666 --rpcport 8545 console 2>geth.txt

Android studio新建專案並新增.jar包。jar包下載

佈局如下：

<Buttonandroid:id="@+id/showView"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="getBlock"/><TextViewandroid:layout_width="match_parent"android:layout_height="match_parent"android:id="@+id/textview"/>

MainActivity如下：

package com.ethereum;

import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.Button;import android.widget.TextView;

import org.alexd.jsonrpc.JSONRPCException;import org.alexd.jsonrpc.JSONRPCHttpClient;

import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

privateButton showButton;privateTextView textview;publicstaticfinalint SHOW =0;privateHandler handler =newHandler(){publicvoid handleMessage(Message msg){switch(msg.what){case SHOW:String a =(String) msg.obj;
                textview.setText(a);}}};[@Override](/user/Override)protectedvoid onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    textview=(TextView)findViewById(R.id.textview);
    showButton =(Button) findViewById(R.id.showView);
    showButton.setOnClickListener(this);}[@Override](/user/Override)publicvoid onClick(View v){if(v.getId()== R.id.showView){
        show();}}privatevoid show(){newThread(newRunnable(){[@Override](/user/Override)publicvoid run(){try{String url ="http://10.0.2.2:8545";JSONRPCHttpClient client =newJSONRPCHttpClient(url);Map<String,Object> map =newHashMap();List paramsList =newArrayList();
                map.put("json-rpc","2.0");
                map.put("method","web3_clientVersion");
                map.put("params", paramsList);
                map.put("id","67");String st = client.callString("web3_clientVersion", map);Message msg =newMessage();
                msg.what =SHOW;
                msg.obj = st;
                handler.sendMessage(msg);}catch(JSONRPCException e){
                e.printStackTrace();}}}).start();}

}

新增許可權：

<uses-permission android:name="android.permission.INTERNET"/>

點選Button以後結果：