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      安卓系列教程之ROM系统开发-百问100ask

说明

系统：Android10.0

设备： FireFly RK3399 （ROC-RK3399-PC-PLUS）

前言

上一节介绍了属性操作的各个API， 本章节通过实战代码来演示如何应用属性。

---

一， C/C++代码

目标：

1，在代码中获取当前系统的版本

2，为adbd设置tcp连接的端口，并使其生效, 此处会操作属性ctrl.start和ctrl.stop

代码文件： 

Android.mk 

prop_test.cpp

实例代码

mytest/property_test$ vim prop_test.cpp：

#include 
#include 
 
// for c
#include 
#define LOG_TAG "prop_test"
#include 
 
#include 
 
// for adb
#define ADBD_TCP_DEFAULT_PORT  15000
#define PROP_ADBD_TCP_PORT "service.adb.tcp.port"
 
using   namespace  std;
 
void print_android_version()
{
    char android_version[PROPERTY_VALUE_MAX];
    property_get("ro.build.version.release", android_version, "");
 
    ALOGD("android version : %s", android_version);
 
}
 
void  set_adbd_tcp_port(unsigned int port){
    if(port <= 10000)
        port = ADBD_TCP_DEFAULT_PORT;
    property_set(PROP_ADBD_TCP_PORT, std::to_string(port).c_str());
 
 
}
 
void CplusTestPropString()
{
 
    const char* test_props[] = {
        "ro.product.name",
        "ro.product.model",
        "ro.product.device",
    };
 
    for (const auto& prop : test_props) {
        std::string value = std::string(prop) + "=" + android::base::GetProperty(prop, "");
    ALOGD("CPlUS API--%s", value.c_str());
    }
 
}
 
 
 
int main(int argc, char *argv[])
{
    print_android_version();
    CplusTestPropString();
 
    set_adbd_tcp_port(0);
    property_set("ctrl.stop", "adbd");
    property_set("ctrl.start", "adbd");
 
    return 0;
}

mytest/property_test$ vim Android.mk

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
 
LOCAL_CFLAGS += \
                -Wno-error \
                -Wno-unused-parameter
 
 
LOCAL_SHARED_LIBRARIES := \
        libbase \
        libcutils \
        liblog \
 
 
 
LOCAL_SRC_FILES:= prop_test.cpp
 
LOCAL_MODULE:= prop_test
 
include $(BUILD_EXECUTABLE)

 编译： 

rk3399_Android10.0$ source FFTools/build.s

rk3399_Android10.0$ lunch qh100_rk3399-userdebug

rk3399_Android10.0$ mmma mytest/property_test/

生成的目标文件： 

[100% 540/540] Install: out/target/product/qh100_rk3399/system/bin/prop_test

通过adb push将文件推送到/system/bin/目录下进行运行。

qh100_rk3399:/ # logcat -s property_test
--------- beginning of main
08-17 12:20:24.812  1894  1894 D property_test: android version : 10
08-17 12:20:24.812  1894  1894 D property_test: CPlUS API--ro.product.name=qh100_rk3399
08-17 12:20:24.812  1894  1894 D property_test: CPlUS API--ro.product.model=qh100
08-17 12:20:24.812  1894  1894 D property_test: CPlUS API--ro.product.device=qh100_rk3399

二，java代码示例

目标： 1， 通过Build类获取到相关属性

2， 通过反射机制获取到属性

PropertyTest\app\src\main\java\com\qh\propertytest\MainActivity.java

package com.qh.propertytest;
 
import androidx.appcompat.app.AppCompatActivity;
 
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
 
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private Button btn_build_info;
    private Button btn_get_prop;
    private Button btn_set_prop;
    private TextView tv_show;
 
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        initUI();
    }
 
    private void initUI() {
        btn_build_info= (Button)findViewById(R.id.btn_build_info);
        btn_build_info.setOnClickListener(this);
        btn_get_prop= (Button)findViewById(R.id.btn_get_prop);
        btn_get_prop.setOnClickListener(this);
        btn_set_prop = (Button)findViewById(R.id.btn_set_prop);
        btn_set_prop.setOnClickListener(this);
        tv_show= (TextView) findViewById(R.id.tv_show);
 
    }
 
    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.btn_build_info:
                tv_show.setText(PropertyUitls.getBuildDeviceListing());
 
                break;
            case R.id.btn_get_prop:
                tv_show.setText(PropertyUitls.getPropertyListing());
                break;
            case R.id.btn_set_prop:
                PropertyUitls.setProperty("my.second.name", "lilei");
                tv_show.setText(PropertyUitls.getProperty("my.second.name", ""));
                break;
        }
    }
}

PropertyTest\app\src\main\java\com\qh\propertytest\PropertyUitls.java

package com.qh.propertytest;
 
import android.os.Build;
 
import java.lang.reflect.Method;
 
public class PropertyUitls {
    private static  final int PROP_VALUE_MAX = 91;
 
    public static String getProperty(String key, String defaultValue) {
        String value = defaultValue;
        try {
            Class c = Class.forName("android.os.SystemProperties");
            Method get = c.getMethod("get", String.class, String.class);
            value = (String)(get.invoke(c, key, defaultValue));
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            return value;
        }
    }
    public static void setProperty(String key, String val) {
 
        if (val != null && !val.startsWith("ro.") && val.length() > PROP_VALUE_MAX) {
            throw new IllegalArgumentException("value of system property '" + key
                    + "' is longer than " + PROP_VALUE_MAX + " characters: " + val);
        }
        try {
            Class c = Class.forName("android.os.SystemProperties");
            Method set = c.getMethod("set", String.class, String.class);
            set.invoke(c, key, val);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
        }
    }
 
    public static String getBuildDeviceListing() {
        return "Build.PRODUCT: " + Build.PRODUCT + "\n" +
                "Build.MANUFACTURER: " + Build.MANUFACTURER + "\n" +
                "Build.BRAND: " + Build.BRAND + "\n" +
                "Build.DEVICE: " + Build.DEVICE + "\n" +
                "Build.MODEL: " + Build.MODEL + "\n" +
                "Build.HARDWARE: " + Build.HARDWARE + "\n" +
                "Build.FINGERPRINT: " + Build.FINGERPRINT + "\n" +
                "Build.TAGS: " + Build.TAGS + "\n";
    }
 
    public static String getPropertyListing() {
        return "ro.hardware: " + getProperty("ro.hardware", "") + "\n" +
                "ro.product.model: " + getProperty("ro.product.model", "") + "\n" +
                "ro.product.manufacturer: " + getProperty("ro.product.manufacturer", "") + "\n" +
                "ro.product.board: " + getProperty("ro.product.board", "") + "\n" +
                "init.svc.adbd: " + getProperty("init.svc.adbd", "") + "\n" ;
    }
 
}

点击BUILDSHOW按钮的结果 

点击PROP_SHOW按钮的结果

点击PROP_SET按钮的结果