How to select a stream object?

1. Clarify the source and purpose

Source: input stream

Inputstream

Reader

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Objective: To output a stream

Outputstream

Writer

 

2. Whether the operated data is plain text

Yes: Batch stream

No: byte stream

 

3. When the system is clear, specify the specific object to use.

Distinguish between source devices:

1. Memory

2. Hard Disk

3. keyboard

Target device:

1. Memory

2. Hard Disk

3. Console

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1. Copy an object

Source: because it is the source, the read stream is used. Inputstream Reader

Is it a text file operation?

Yes, then you can choose reader, so that the system is clear. ,

 

Next, identify the object in the system,

Device: hard disk, the last file.

In the reader system, the object that can operate files is filereader.

Filereader Fr = new filereader(“a.txt ");

Need to improve efficiency? Yes. Join the buffer zone in the reader system.

Bufferedreader bufr = new bufferedreader (FR );

 

 

 

Purpose: outputstream writer

Whether it is plain text

Yes. Writer

Device: hard disk, a file.

In the writer system, filewriter can operate files.

Filewriter fw = new filewriter(“ B .txt ");

Need to improve efficiency? Yes, just join the buffer in the writer System

Bufferedwriter bufw = new bufferedwriter (FW );

 

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Requirement: Save the data entered by the keyboard to a file

Source: inputstream Reader

1. Is it plain text? Yes, Reader

2. device? Keyboard. The corresponding object is system. In.

Didn't you select reader? Does system. In correspond to a byte stream?

In order to operate the text data of the keyboard conveniently, it is most convenient to convert the data into a text stream according to the string. Therefore, since reader is clearly defined, system. In is converted to reader.

Reader System Conversion stream is used. Inputstreamreader

Inputstreamreader ISR = new inputstreamreader (system. In );

Need to improve efficiency?

Bufferedreader bufr = new bufferedreader (ISR );

 

Purpose: outputstream writer

Is text stored? Yes, writer

Device? Hard disk, a file-> filewriter

Filewriter fw = new filewriter()a.txt ");

Need to improve efficiency? Yes

Bufferedwriter bufw = new bufferedwriter (FW );

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Expand to store the entered data according to the specified encoding.

Purpose:

Save text? Yes, writer

 

Device: hard disk, a file filewriter. However, filewriter uses the default encoding table. Encoding must be specified during storage. outputstreamwriter can specify encoding.

 

Outputstreamwriter OSW = new outputstreamwriter (New fileoutputstream(mongod.txt "," UTF-8 "));

Need efficiency?

Bufferedwriter bufw = new bufferedwriter (OSW );

So remember, when to use the conversion stream, the bridge between characters and bytes. Generally, the conversion stream is required when character encoding conversion is involved.