分别编译frameworks/base/packages/SettingsProvider 与 frameworks/base
编译后push 到 system/priv-app/SettingsProvider/SettingsProvider.apk system/framework/framework.jar
删去机器中对应的oat目录。重启或恢复出厂设置。第一次开机时，会先出现status bar，launcher要等一会才出来。
之后重启就可以直接进入launcher。机器会默认不锁屏。但还是会进入sleep状态。
源码流程：
frameworks/base/packages/SettingsProvider/src/com/android/providers/settings/DatabaseHelper.java
if (upgradeVersion == 54)// 版本为54才会设置timeout
......
private void upgradeScreenTimeoutFromNever(SQLiteDatabase db) {
// See if the timeout is -1 (for "Never").
Cursor c = db.query(TABLE_SYSTEM, new String[] { "_id", "value" }, "name=? AND value=?",
new String[] { Settings.System.SCREEN_OFF_TIMEOUT, "-1" },
null, null, null);
SQLiteStatement stmt = null;
if (c.getCount() > 0) {
c.close();
try {
stmt = db.compileStatement("INSERT OR REPLACE INTO system(name,value)"
+ " VALUES(?,?);");
// Set the timeout to 30 minutes in milliseconds
loadSetting(stmt, Settings.System.SCREEN_OFF_TIMEOUT,
Integer.toString(30 * 60 * 1000));
} finally {
if (stmt != null) stmt.close();
}
} else {
c.close();
}
}
......
if (SystemProperties.getBoolean("ro.lockscreen.disable.default", false) == true) {
loadSetting(stmt, Settings.System.LOCKSCREEN_DISABLED, "1");
} else {
loadBooleanSetting(stmt, Settings.System.LOCKSCREEN_DISABLED,
R.bool.def_lockscreen_disabled);
}
timeout若是-1，则永不锁屏
读取"ro.lockscreen.disable.default"，如果默认为true，则设置禁止锁屏；否则从xml中读配置
frameworks/base/packages/SettingsProvider/res/values/defaults.xml <integer name="def_screen_off_timeout">60000</integer> <bool name="def_lockscreen_disabled">false</bool>`
