adb 端口自定义及原理说明

日常开发的时候，adb端口经常被一些其他程序占用，譬如一些手机助手软件会频繁的导致5037端口不可用，其实我们可以自定义adb的端口，而且一劳永逸，不用在频繁的 adb kill-server的命令 或者查找占用端口的进程去杀掉，这也太麻烦。

• win系统配置ANDROID_ADB_SERVER_PORT

在系统环境变量中定义 ANDROID_ADB_SERVER_PORT 的值即可，这样adb在运行的时候回使用我们配置的ANDROID_ADB_SERVER_PORT值，而不是原来默认的5037这个端口，

• 配置ANDROID_ADB_SERVER_PORT作用

大家好奇为啥通过配置ANDROID_ADB_SERVER_PORT就可以修改adb的端口,看看adb的源码

    private static final String SERVER_PORT_ENV_VAR = "ANDROID_ADB_SERVER_PORT"; //$NON-NLS-1$
    // Where to find the ADB bridge.
    static final String DEFAULT_ADB_HOST = "127.0.0.1"; //$NON-NLS-1$
    static final int DEFAULT_ADB_PORT = 5037;//默认端口
    
    /**
     * Returns the port where adb server should be launched. This looks at:
     * <ol>
     *     <li>The system property ANDROID_ADB_SERVER_PORT</li>
     *     <li>The environment variable ANDROID_ADB_SERVER_PORT</li>
     *     <li>Defaults to {@link #DEFAULT_ADB_PORT} if neither the system property nor the env var
     *     are set.</li>
     * </ol>
     *
     * @return The port number where the host's adb should be expected or started.
     */
    private static int getAdbServerPort() {
        // check system property
        Integer prop = Integer.getInteger(SERVER_PORT_ENV_VAR);
        if (prop != null) {
            try {
                return validateAdbServerPort(prop.toString());
            } catch (IllegalArgumentException e) {
                String msg = String.format(
                        "Invalid value (%1$s) for ANDROID_ADB_SERVER_PORT system property.",
                        prop);
                Log.w(DDMS, msg);
            }
        }
        // when system property is not set or is invalid, parse environment property
        try {
            String env = System.getenv(SERVER_PORT_ENV_VAR);
            if (env != null) {
                return validateAdbServerPort(env);
            }
        } catch (SecurityException ex) {
            // A security manager has been installed that doesn't allow access to env vars.
            // So an environment variable might have been set, but we can't tell.
            // Let's log a warning and continue with ADB's default port.
            // The issue is that adb would be started (by the forked process having access
            // to the env vars) on the desired port, but within this process, we can't figure out
            // what that port is. However, a security manager not granting access to env vars
            // but allowing to fork is a rare and interesting configuration, so the right
            // thing seems to be to continue using the default port, as forking is likely to
            // fail later on in the scenario of the security manager.
            Log.w(DDMS,
                    "No access to env variables allowed by current security manager. "
                            + "If you've set ANDROID_ADB_SERVER_PORT: it's being ignored.");
        } catch (IllegalArgumentException e) {
            String msg = String.format(
                    "Invalid value (%1$s) for ANDROID_ADB_SERVER_PORT environment variable (%2$s).",
                    prop, e.getMessage());
            Log.w(DDMS, msg);
        }
        // use default port if neither are set
        return DEFAULT_ADB_PORT;
    }
复制代码

上面的只是截取了主要获取端口号的方法getAdbServerPort（），该方法首先获取操作系统属性ANDROID_ADB_SERVER_PORT配置的值，如果找到就返回，否则才会返回默认的值DEFAULT_ADB_PORT，也是5037这个端口，所有我们通过配置ANDROID_ADB_SERVER_PORT是可以修改adb端口的目的

如果配置完ANDROID_ADB_SERVER_PORT该属性，检测不到设备的话，重启一下电脑就好

完整源码连接