Android V7包学习笔记更新中.....

Android V7包学习笔记更新中.....

关于V4 V7 V13

VX包介绍转自这里
1, Android Support V4, V7, V13是什么？
本质上就是三个java library。

2, 为什么要有support库？
如果在低版本Android平台上开发一个应用程序，而应用程序又想使用高版本才拥有的功能，就需要使用Support库。

3, 三个Support 库的区别和作用是什么？
Android Support v4 是最早（2011年4月份）实现的库。用在Android1.6 (API lever 4)或者更高版本之上。它包含了相对V4, V13大的多的功能。
例如：Fragment，NotificationCompat，LoadBroadcastManager，ViewPager，PageTabAtrip，Loader，FileProvider 等。
详细API 参考 http://developer.android.com/reference/android/support/v4/app/package-summary.html
Android Support v7: 这个包是为了考虑Android2.1(API level 7) 及以上版本而设计的，但是v7是要依赖v4这个包的，也就是如果要使用，两个包得同时 被引用。
v7支持了Action Bar。
Android Support v13:这个包的设计是为了android 3.2及更高版本的，一般我们都不常用，平板开发中能用到。

sdk\extras\android\support\samples\Support7Demos笔记

FloatingActionButton

代码分析：
Logger包
关于log：需要使用Log输出一些信息。那么我们就需要使用到Log FrameWork。使用及注释如下

  public void initializeLogging() {
        //封装android底层log框架
        LogWrapper logWrapper = new LogWrapper();
        // Using Log, front-end to the logging chain, emulates android.util.log method signatures.
        /**
         * Log的消息传递是依据一个链路依次传递的，Log传递到LogWrapper，LogWrapper传递到MessageOnlyLogFilter，MessageOnlyLogFilter传递到LogFragment
         */

        Log.setLogNode(logWrapper);

        // 过滤器
        MessageOnlyLogFilter msgFilter = new MessageOnlyLogFilter();
        logWrapper.setNext(msgFilter);

        // On screen logging via a fragment with a TextView.
        LogFragment logFragment = (LogFragment) getSupportFragmentManager()
                .findFragmentById(R.id.log_fragment);
        msgFilter.setNext(logFragment.getLogView());
        Log.i(TAG, "Ready");
    }

涉及到的主要的类：

package com.example.android.common.logger;

/**
 * Helper class for a list (or tree) of LoggerNodes.
 *
 * 
When this is set as the head of the list,
 * an instance of it can function as a drop-in replacement for {@link android.util.Log}.
 * Most of the methods in this class server only to map a method call in Log to its equivalent
 * in LogNode.
 */
public class Log {
    // Grabbing the native values from Android's native logging facilities,
    // to make for easy migration and interop.
    public static final int NONE = -1;
    public static final int VERBOSE = android.util.Log.VERBOSE;
    public static final int DEBUG = android.util.Log.DEBUG;
    public static final int INFO = android.util.Log.INFO;
    public static final int WARN = android.util.Log.WARN;
    public static final int ERROR = android.util.Log.ERROR;
    public static final int ASSERT = android.util.Log.ASSERT;

    // Stores the beginning of the LogNode topology.
    private static LogNode mLogNode;

    /**
     * Returns the next LogNode in the linked list.
     */
    public static LogNode getLogNode() {
        return mLogNode;
    }

    /**
     * Sets the LogNode data will be sent to.
     */
    public static void setLogNode(LogNode node) {
        mLogNode = node;
    }

    /**
     * Instructs the LogNode to print the log data provided. Other LogNodes can
     * be chained to the end of the LogNode as desired.
     *
     * @param priority Log level of the data being logged. Verbose, Error, etc.
     * @param tag Tag for for the log data. Can be used to organize log statements.
     * @param msg The actual message to be logged.
     * @param tr If an exception was thrown, this can be sent along for the logging facilities
     *           to extract and print useful information.
     */
    public static void println(int priority, String tag, String msg, Throwable tr) {
        if (mLogNode != null) {
            mLogNode.println(priority, tag, msg, tr);
        }
    }

    /**
     * Instructs the LogNode to print the log data provided. Other LogNodes can
     * be chained to the end of the LogNode as desired.
     *
     * @param priority Log level of the data being logged. Verbose, Error, etc.
     * @param tag Tag for for the log data. Can be used to organize log statements.
     * @param msg The actual message to be logged. The actual message to be logged.
     */
    public static void println(int priority, String tag, String msg) {
        println(priority, tag, msg, null);
    }

   /**
     * Prints a message at VERBOSE priority.
     *
     * @param tag Tag for for the log data. Can be used to organize log statements.
     * @param msg The actual message to be logged.
     * @param tr If an exception was thrown, this can be sent along for the logging facilities
     *           to extract and print useful information.
     */
    public static void v(String tag, String msg, Throwable tr) {
        println(VERBOSE, tag, msg, tr);
    }

    /**
     * Prints a message at VERBOSE priority.
     *
     * @param tag Tag for for the log data. Can be used to organize log statements.
     * @param msg The actual message to be logged.
     */
    public static void v(String tag, String msg) {
        v(tag, msg, null);
    }


    /**
     * Prints a message at DEBUG priority.
     *
     * @param tag Tag for for the log data. Can be used to organize log statements.
     * @param msg The actual message to be logged.
     * @param tr If an exception was thrown, this can be sent along for the logging facilities
     *           to extract and print useful information.
     */
    public static void d(String tag, String msg, Throwable tr) {
        println(DEBUG, tag, msg, tr);
    }

    /**
     * Prints a message at DEBUG priority.
     *
     * @param tag Tag for for the log data. Can be used to organize log statements.
     * @param msg The actual message to be logged.
     */
    public static void d(String tag, String msg) {
        d(tag, msg, null);
    }

    /**
     * Prints a message at INFO priority.
     *
     * @param tag Tag for for the log data. Can be used to organize log statements.
     * @param msg The actual message to be logged.
     * @param tr If an exception was thrown, this can be sent along for the logging facilities
     *           to extract and print useful information.
     */
    public static void i(String tag, String msg, Throwable tr) {
        println(INFO, tag, msg, tr);
    }

    /**
     * Prints a message at INFO priority.
     *
     * @param tag Tag for for the log data. Can be used to organize log statements.
     * @param msg The actual message to be logged.
     */
    public static void i(String tag, String msg) {
        i(tag, msg, null);
    }

    /**
     * Prints a message at WARN priority.
     *
     * @param tag Tag for for the log data. Can be used to organize log statements.
     * @param msg The actual message to be logged.
     * @param tr If an exception was thrown, this can be sent along for the logging facilities
     *           to extract and print useful information.
     */
    public static void w(String tag, String msg, Throwable tr) {
        println(WARN, tag, msg, tr);
    }

    /**
     * Prints a message at WARN priority.
     *
     * @param tag Tag for for the log data. Can be used to organize log statements.
     * @param msg The actual message to be logged.
     */
    public static void w(String tag, String msg) {
        w(tag, msg, null);
    }

    /**
     * Prints a message at WARN priority.
     *