Android中Serializable和Parcelable序列化对象详解

public class Person implements Serializable{
 private static final long serialVersionUID = -7060210544600464481L;
 private String name;
 private int age;
  
 public String getName(){
  return name;
 }
  
 public void setName(String name){
  this.name = name;
 }
  
 public int getAge(){
  return age;
 }
  
 public void setAge(int age){
  this.age = age;
 }
}

public class Book implements Parcelable{
 private String bookName;
 private String author;
 private int publishDate;
  
 public Book(){
   
 }
  
 public String getBookName(){
  return bookName;
 }
  
 public void setBookName(String bookName){
  this.bookName = bookName;
 }
  
 public String getAuthor(){
  return author;
 }
  
 public void setAuthor(String author){
  this.author = author;
 }
  
 public int getPublishDate(){
  return publishDate;
 }
  
 public void setPublishDate(int publishDate){
  this.publishDate = publishDate;
 }
  
 @Override
 public int describeContents(){
  return 0;
 }
  
 @Override
 public void writeToParcel(Parcel out, int flags){
  out.writeString(bookName);
  out.writeString(author);
  out.writeInt(publishDate);
 }
  
 public static final Parcelable.Creator<Book> CREATOR = new Creator<Book>(){
   
　　　　 @Override
  public Book[] newArray(int size){
   return new Book[size];
  }
   
  @Override
  public Book createFromParcel(Parcel in){
   return new Book(in);
  }
 };
  
 public Book(Parcel in){
  //如果元素数据是list类型的时候需要： lits = new ArrayList<?> in.readList(list); 
  //否则会出现空指针异常.并且读出和写入的数据类型必须相同.如果不想对部分关键字进行序列化,可以使用transient关键字来修饰以及static修饰.
  bookName = in.readString();
  author = in.readString();
  publishDate = in.readInt();
 }
}

static jint android_os_Parcel_readInt(JNIEnv* env, jobject clazz){
 Parcel* parcel = parcelForJavaObject(env, clazz);
 if (parcel != NULL) {
  return parcel->readInt32();
 }
 return 0;
}

status_t Parcel::writeInt32(int32_t val){
 return writeAligned(val);
} 
template<class t="">
status_t Parcel::writeAligned(T val) {
 COMPILE_TIME_ASSERT_FUNCTION_SCOPE(PAD_SIZE(sizeof(T)) == sizeof(T));
  
 if ((mDataPos+sizeof(val)) <= mDataCapacity) {
restart_write:
  *reinterpret_cast<t*>(mData+mDataPos) = val;
  return finishWrite(sizeof(val));
 }
  
 status_t err = growData(sizeof(val));
 if (err == NO_ERROR) goto restart_write;
 return err;
}
真正的读写过程是由下面的源代码来完成的.
status_t Parcel::continueWrite(size_t desired)
{
 // If shrinking, first adjust for any objects that appear
 // after the new data size.
 size_t objectsSize = mObjectsSize;
 if (desired < mDataSize) {
  if (desired == 0) {
   objectsSize = 0;
  } else {
   while (objectsSize > 0) {
    if (mObjects[objectsSize-1] < desired)
     break;
    objectsSize--;
   }
  }
 }
  
 if (mOwner) {
  // If the size is going to zero, just release the owner‘s data.
  if (desired == 0) {
   freeData();
   return NO_ERROR;
  }
 
  // If there is a different owner, we need to take
  // posession.
  uint8_t* data = (uint8_t*)malloc(desired);
  if (!data) {
   mError = NO_MEMORY;
   return NO_MEMORY;
  }
  size_t* objects = NULL;
   
  if (objectsSize) {
   objects = (size_t*)malloc(objectsSize*sizeof(size_t));
   if (!objects) {
    mError = NO_MEMORY;
    return NO_MEMORY;
   }
 
   // Little hack to only acquire references on objects
   // we will be keeping.
   size_t oldObjectsSize = mObjectsSize;
   mObjectsSize = objectsSize;
   acquireObjects();
   mObjectsSize = oldObjectsSize;
  }
   
  if (mData) {
   memcpy(data, mData, mDataSize < desired ? mDataSize : desired);
  }
  if (objects && mObjects) {
   memcpy(objects, mObjects, objectsSize*sizeof(size_t));
  }
  //ALOGI("Freeing data ref of %p (pid=%d)\n", this, getpid());
  mOwner(this, mData, mDataSize, mObjects, mObjectsSize, mOwnerCookie);
  mOwner = NULL;
 
  mData = data;
  mObjects = objects;
  mDataSize = (mDataSize < desired) ? mDataSize : desired;
  ALOGV("continueWrite Setting data size of %p to %d\n", this, mDataSize);
  mDataCapacity = desired;
  mObjectsSize = mObjectsCapacity = objectsSize;
  mNextObjectHint = 0;
 
 } else if (mData) {
  if (objectsSize < mObjectsSize) {
   // Need to release refs on any objects we are dropping.
   const sp<ProcessState> proc(ProcessState::self());
   for (size_t i=objectsSize; i<mObjectsSize; i++) {
    const flat_binder_object* flat
     = reinterpret_cast<flat_binder_object*>(mData+mObjects[i]);
    if (flat->type == BINDER_TYPE_FD) {
     // will need to rescan because we may have lopped off the only FDs
     mFdsKnown = false;
    }
    release_object(proc, *flat, this);
   }
   size_t* objects =
    (size_t*)realloc(mObjects, objectsSize*sizeof(size_t));
   if (objects) {
    mObjects = objects;
   }
   mObjectsSize = objectsSize;
   mNextObjectHint = 0;
  }
 
  // We own the data, so we can just do a realloc().
  if (desired > mDataCapacity) {
   uint8_t* data = (uint8_t*)realloc(mData, desired);
   if (data) {
    mData = data;
    mDataCapacity = desired;
   } else if (desired > mDataCapacity) {
    mError = NO_MEMORY;
    return NO_MEMORY;
   }
  } else {
   if (mDataSize > desired) {
    mDataSize = desired;
    ALOGV("continueWrite Setting data size of %p to %d\n", this, mDataSize);
   }
   if (mDataPos > desired) {
    mDataPos = desired;
    ALOGV("continueWrite Setting data pos of %p to %d\n", this, mDataPos);
   }
  }
   
 } else {
  // This is the first data. Easy!
  uint8_t* data = (uint8_t*)malloc(desired);
  if (!data) {
   mError = NO_MEMORY;
   return NO_MEMORY;
  }
   
  if(!(mDataCapacity == 0 && mObjects == NULL
    && mObjectsCapacity == 0)) {
   ALOGE("continueWrite: %d/%p/%d/%d", mDataCapacity, mObjects, mObjectsCapacity, desired);
  }
   
  mData = data;
  mDataSize = mDataPos = 0;
  ALOGV("continueWrite Setting data size of %p to %d\n", this, mDataSize);
  ALOGV("continueWrite Setting data pos of %p to %d\n", this, mDataPos);
  mDataCapacity = desired;
 }
 
 return NO_ERROR;
}

public class Book implements Parcelable{
 private String bookName;
 private String author;
 private int publishDate;
  
 public Book(){
   
 }
  
 public String getBookName(){
  return bookName;
 }
  
 public void setBookName(String bookName){
  this.bookName = bookName;
 }
  
 public String getAuthor(){
  return author;
 }
  
 public void setAuthor(String author){
  this.author = author;
 }
  
 public int getPublishDate(){
  return publishDate;
 }
  
 public void setPublishDate(int publishDate){
  this.publishDate = publishDate;
 }
  
 @Override
 public int describeContents(){
  return 0;
 }
  
 @Override
 public void writeToParcel(Parcel out, int flags){
  out.writeString(bookName);
  out.writeString(author);
  out.writeInt(publishDate);
 }
  
 public static final Parcelable.Creator<Book> CREATOR = new Creator<Book>(){
   
　　　　 @Override
  public Book[] newArray(int size){
   return new Book[size];
  }
   
  @Override
  public Book createFromParcel(Parcel in){
   return new Book(in);
  }
 };
  
 public Book(Parcel in){
  //如果元素数据是list类型的时候需要： lits = new ArrayList<?> in.readList(list); 否则会出现空指针异常.并且读出和写入的数据类型必须相同.如果不想对部分关键字进行序列化,可以使用transient关键字来修饰以及static修饰.
  bookName = in.readString();
  author = in.readString();
  publishDate = in.readInt();
 }
}

Book book = new Book();
book.setBookname("Darker");
book.setBookauthor("me");
book.setPublishDate(20);
Bundle bundle = new Bundle();
bundle.putParcelable("book", book);
Intent intent = new Intent(MainActivity.this,AnotherActivity.class);
intent.putExtras(bundle);

Intent intent = getIntent();
Bundle bun = intent.getExtras();
Book book = bun.getParcelable("book");
System.out.println(book);