Android 實現Parcelable介面序列化物件
阿新 • • 發佈:2019-02-13
關於物件序列化的方法,在Android中常用到的一般有兩種,一種是可以通過實現Serializable介面,這也是java語言中常用的序列化方法,別外一種就是實現Parcelable介面,這是android所特有的。這兩個介面,實現Serializable介面相對簡單,宣告一下就可以了,而實現Parcelable介面相對要複雜一些,但是android過程中,效率較Serializable要高一些,所以推薦使用實現Parcelable介面的方法來序列化物件。
通過Parcelable介面序列化物件一般要通過以下幾個步驟:
1,宣告實現Parcelable介面。
2,覆寫writeToParcel方法,將物件序列化為Parcel物件。
3,實現內部Parcelable.Creator<T>物件,覆寫createFromParcel方法,來將物件反序列化。
下面貼上Android程式碼中通過實現Parcelable介面序列化物件的例子:
/* * Copyright (C) 2009 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package android.accounts; import android.os.Parcelable; import android.os.Parcel; import android.text.TextUtils; /** * Value type that represents an Account in the {@link AccountManager}. This object is * {@link Parcelable} and also overrides {@link #equals} and {@link #hashCode}, making it * suitable for use as the key of a {@link java.util.Map} */ public class Account implements Parcelable { public final String name; public final String type; public boolean equals(Object o) { if (o == this) return true; if (!(o instanceof Account)) return false; final Account other = (Account)o; return name.equals(other.name) && type.equals(other.type); } public int hashCode() { int result = 17; result = 31 * result + name.hashCode(); result = 31 * result + type.hashCode(); return result; } public Account(String name, String type) { if (TextUtils.isEmpty(name)) { throw new IllegalArgumentException("the name must not be empty: " + name); } if (TextUtils.isEmpty(type)) { throw new IllegalArgumentException("the type must not be empty: " + type); } this.name = name; this.type = type; } public Account(Parcel in) { this.name = in.readString(); this.type = in.readString(); } public int describeContents() { return 0; } public void writeToParcel(Parcel dest, int flags) { dest.writeString(name); dest.writeString(type); } public static final Creator<Account> CREATOR = new Creator<Account>() { public Account createFromParcel(Parcel source) { return new Account(source); } public Account[] newArray(int size) { return new Account[size]; } }; public String toString() { return "Account {name=" + name + ", type=" + type + "}"; } }
物件序列化的一個好處,就是可以很方便的通過Intent來傳遞資料,可以直接傳遞一個物件,也可以通過putParcelableArrayListExtra方法,直接傳遞一個序列化物件的陣列。