Intent 传数据

Intent作为android重要的组件其重要性不言而喻，这里说说他是怎么传递简单数据和对象

    Intent的具体概念就不讲解了！网上有很多的

• 传递简单的数据(例如String,float等)
• 传递对象(利用Serializable接口) 
• 传递对象(利用Parcelable接口)

　　传对象时候至于选取哪种可参考下面的原则：

　　　　1.在使用内存的时候，Parcelable 类比Serializable性能高，所以推荐使用Parcelable类。
　　　　2.Serializable在序列化的时候会产生大量的临时变量，从而引起频繁的GC。
　　　　3.Parcelable不能使用在要将数据存储在磁盘上的情况，因为Parcelable不能很好的保证数据的持续性在外界有变化的情况下。尽管Serializable效率低点， 也不提倡用，但在这种情况下，还是建议你用Serializable

 　  下面就通过一个简单的例子来进行传值：

　　MainActivity包含了三个按钮分别用来传递简单数据和对象和另外的对象。XML文件就是三个Button就不贴出来了

　　

public class MainActivity extends Activity implements OnClickListener {

    Button btn1 = null;
    Button btn2 = null;
    Button btn3 = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btn1 = (Button) findViewById(R.id.button1);
        btn2 = (Button) findViewById(R.id.button2);
        btn3 = (Button) findViewById(R.id.button3);

        btn1.setOnClickListener(this);
        btn2.setOnClickListener(this);
        btn3.setOnClickListener(this);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
        case R.id.button1:
            Intent intent1 = new Intent();
            intent1.putExtra("name", "西瓜");
            intent1.putExtra("color", "红加绿");
            intent1.putExtra("price", 10);
            intent1.setClass(MainActivity.this, MessageActivity.class);
            startActivity(intent1);
            break;
        case R.id.button2:
            Intent intent2 = new Intent();
            Bundle bundle = new Bundle();
            apple ap = new apple();
            ap.setColor("红色");
            ap.setName("苹果");
            ap.setPrice(15);
            bundle.putSerializable("fruit", ap);
            intent2.putExtras(bundle);
            intent2.setClass(MainActivity.this, AppleActivity.class);
            startActivity(intent2);
            break;
        case R.id.button3:
            Intent intent3 = new Intent();
            Bundle bundle2 = new Bundle();
            orange or = new orange();
            or.setFruitColor("橘黄色");
            or.setName("橘子");
            or.setPrice(12);
            bundle2.putParcelable("orange", or);
            intent3.putExtras(bundle2);
            intent3.setClass(MainActivity.this, OrangeActivity.class);
            startActivity(intent3);
            break;
        default:
            break;

        }

    }

}

 

　　每个Button转向的Activity

　　简单数据的Activity是MessageActivity，利用Serializable传对的Activity是AppleActivity ，利用Parcelable传对的Activity是OrangeActivity

　　他们XML文件当中都是有三个TextView 就不贴出来了

　　　　MessageActivity：

public class MessageActivity extends Activity {

    TextView text1 = null;
    TextView text2 = null;
    TextView text3 = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_message);

        text1 = (TextView) findViewById(R.id.Name);
        text2 = (TextView) findViewById(R.id.Price);
        text3 = (TextView) findViewById(R.id.Color);
        
        Intent intent = getIntent();
        text1.setText(intent.getStringExtra("name"));
        text2.setText(intent.getFloatExtra("price", 5)+"");
        text3.setText(intent.getStringExtra("color"));
        
        
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.message, menu);
        return true;
    }

}

　　　　AppleActivity：

public class AppleActivity extends Activity {

    TextView text1 = null;
    TextView text2 = null;
    TextView text3 = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_apple);
        text1 = (TextView) findViewById(R.id.appleName);
        text2 = (TextView) findViewById(R.id.applePrice);
        text3 = (TextView) findViewById(R.id.appleColor);

        apple ap = (apple) getIntent().getSerializableExtra("fruit");
        text1.setText(ap.getName());
        text2.setText(ap.getPrice() + "");
        text3.setText(ap.getColor());
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.apple, menu);
        return true;
    }

}

　　　　OrangeActivity：

public class OrangeActivity extends Activity {

    TextView text1 = null;
    TextView text2 = null;
    TextView text3 = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_orange);

        text1 = (TextView) findViewById(R.id.orangeName);
        text2 = (TextView) findViewById(R.id.orangePrice);
        text3 = (TextView) findViewById(R.id.orangeColor);

        orange or = (orange) getIntent().getParcelableExtra("orange");

        text1.setText(or.getName());
        text2.setText(or.getPrice() + "");
        text3.setText(or.getFruitColor());

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.orange, menu);
        return true;
    }

}

　　继承Serializable来创建实体类：

public class apple implements Serializable {

    public apple() {
    }

    private String color;
    private String name;
    private float price;

    /**
     * @return the color
     */
    public String getColor() {
        return color;
    }

    /**
     * @param color
     *            the color to set
     */
    public void setColor(String color) {
        this.color = color;
    }

    /**
     * @return the name
     */
    public String getName() {
        return name;
    }

    /**
     * @param name
     *            the name to set
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * @return the price
     */
    public float getPrice() {
        return price;
    }

    /**
     * @param price
     *            the price to set
     */
    public void setPrice(float price) {
        this.price = price;
    }

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return "apple [color=" + color + ", name=" + name + "]";
    }

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.Object#hashCode()
     */
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((color == null) ? 0 : color.hashCode());
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        return result;
    }

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.Object#equals(java.lang.Object)
     */
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        apple other = (apple) obj;
        if (color == null) {
            if (other.color != null)
                return false;
        } else if (!color.equals(other.color))
            return false;
        if (name == null) {
            if (other.name != null)
                return false;
        } else if (!name.equals(other.name))
            return false;
        return true;
    }

}

　　继承Parcelable来创建实体类：  在继承Parcelor创建实体类的时候一定要复杂一些，要注意CREATOR 一定要大写，写小写会报错

public class orange implements Parcelable {

    private String fruitColor;
    private String name;
    private float price;

    public orange() {
    }

    public orange(String fruitColor, String name, float price) {
        this.fruitColor = fruitColor;
        this.name = name;
        this.price = price;
    }

    @Override
    public int describeContents() {
        return 0;
    }

    // 将实体的属性，也就是成员变量保存到parcel当中去
    @Override
    public void writeToParcel(Parcel parcel, int flags) {
        parcel.writeString(fruitColor);
        parcel.writeString(name);
        parcel.writeFloat(price);
    }

    public static final Parcelable.Creator<orange> CREATOR = new Creator<orange>() {

        @Override
        public orange[] newArray(int size) {
            return new orange[size];
        }

        // 从parcel当中恢复实体
        @Override
        public orange createFromParcel(Parcel parcel) {
            // 注意要和成员变量顺序一样
            orange or = new orange();
            or.setFruitColor(parcel.readString());
            or.setName(parcel.readString());
            or.setPrice(parcel.readFloat());
            return or;
        }
    };

    /**
     * @return the fruitColor
     */
    public String getFruitColor() {
        return fruitColor;
    }

    /**
     * @param fruitColor
     *            the fruitColor to set
     */
    public void setFruitColor(String fruitColor) {
        this.fruitColor = fruitColor;
    }

    /**
     * @return the name
     */
    public String getName() {
        return name;
    }

    /**
     * @param name
     *            the name to set
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * @return the price
     */
    public float getPrice() {
        return price;
    }

    /**
     * @param price
     *            the price to set
     */
    public void setPrice(float price) {
        this.price = price;
    }

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return "orange [fruitColor=" + fruitColor + ", name=" + name + "]";
    }

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.Object#hashCode()
     */
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result
                + ((fruitColor == null) ? 0 : fruitColor.hashCode());
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        return result;
    }

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.Object#equals(java.lang.Object)
     */
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        orange other = (orange) obj;
        if (fruitColor == null) {
            if (other.fruitColor != null)
                return false;
        } else if (!fruitColor.equals(other.fruitColor))
            return false;
        if (name == null) {
            if (other.name != null)
                return false;
        } else if (!name.equals(other.name))
            return false;
        return true;
    }

}

     运行后的效果：