MimeHeaders (Apache Tomcat 8.0.15 API Documentation)

java.lang.Object
- org.apache.tomcat.util.http.MimeHeaders

```
public class MimeHeaders
extends Object
```
Memory-efficient repository for Mime Headers. When the object is recycled, it will keep the allocated headers[] and all the MimeHeaderField - no GC is generated. For input headers it is possible to use the MessageByte for Fields - so no GC will be generated. The only garbage is generated when using the String for header names/values - this can't be avoided when the servlet calls header methods, but is easy to avoid inside tomcat. The goal is to use _only_ MessageByte-based Fields, and reduce to 0 the memory overhead of tomcat. TODO: XXX one-buffer parsing - for http ( other protocols don't need that ) XXX remove unused methods XXX External enumerations, with 0 GC. XXX use HeaderName ID

Author:

dac@eng.sun.com, James Todd [gonzo@eng.sun.com], Costin Manolache, kevin seguin

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`DEFAULT_HEADER_SIZE` Initial size - should be == average number of headers per request XXX make it configurable ( fine-tuning of web-apps )

Constructor Summary

Constructors
Constructor and Description

MimeHeaders()
Creates a new MimeHeaders object using a default buffer size.

Constructors
Constructor and Description
`MimeHeaders()` Creates a new MimeHeaders object using a default buffer size.

Method Summary

Methods
Modifier and Type	Method and Description
`MessageBytes`	`addValue(byte[] b, int startN, int len)` Create a new named header using un-translated byte[].
`MessageBytes`	`addValue(String name)` Create a new named header , return the MessageBytes container for the new value
`void`	`clear()` Clears all header fields.
`int`	`findHeader(String name, int starting)` Find the index of a header with the given name.
`String`	`getHeader(String name)`
`MessageBytes`	`getName(int n)` Returns the Nth header name, or null if there is no such header.
`MessageBytes`	`getUniqueValue(String name)` Finds and returns a unique header field with the given name.
`MessageBytes`	`getValue(int n)` Returns the Nth header value, or null if there is no such header.
`MessageBytes`	`getValue(String name)` Finds and returns a header field with the given name.
`Enumeration<String>`	`names()` Returns an enumeration of strings representing the header field names.
`void`	`recycle()` Clears all header fields.
`void`	`removeHeader(String name)` Removes a header field with the specified name.
`void`	`setLimit(int limit)` Set limit on the number of header fields.
`MessageBytes`	`setValue(String name)` Allow "set" operations - return a MessageBytes container for the header value ( existing header or new if this .
`int`	`size()` Returns the current number of header fields.
`String`	`toString()` EXPENSIVE!!!
`Enumeration<String>`	`values(String name)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - DEFAULT_HEADER_SIZE
```
public static final int DEFAULT_HEADER_SIZE
```
    Initial size - should be == average number of headers per request XXX make it configurable ( fine-tuning of web-apps )
    
    See Also:
    Constant Field Values
- Constructor Detail
  - MimeHeaders
```
public MimeHeaders()
```
    Creates a new MimeHeaders object using a default buffer size.
- Method Detail
  - setLimit
```
public void setLimit(int limit)
```
    Set limit on the number of header fields.
  - recycle
```
public void recycle()
```
    Clears all header fields.
  - clear
```
public void clear()
```
    Clears all header fields.
  - toString
```
public String toString()
```
    EXPENSIVE!!! only for debugging.
    
    Overrides:
    
    toString in class Object
  - size
```
public int size()
```
    Returns the current number of header fields.
  - getName
```
public MessageBytes getName(int n)
```
    Returns the Nth header name, or null if there is no such header. This may be used to iterate through all header fields.
  - getValue
```
public MessageBytes getValue(int n)
```
    Returns the Nth header value, or null if there is no such header. This may be used to iterate through all header fields.
  - findHeader
```
public int findHeader(String name,
             int starting)
```
    Find the index of a header with the given name.
  - names
```
public Enumeration<String> names()
```
    Returns an enumeration of strings representing the header field names. Field names may appear multiple times in this enumeration, indicating that multiple fields with that name exist in this header.
  - values
```
public Enumeration<String> values(String name)
```
  - addValue
```
public MessageBytes addValue(String name)
```
    Create a new named header , return the MessageBytes container for the new value
  - addValue
```
public MessageBytes addValue(byte[] b,
                    int startN,
                    int len)
```
    Create a new named header using un-translated byte[]. The conversion to chars can be delayed until encoding is known.
  - setValue
```
public MessageBytes setValue(String name)
```
    Allow "set" operations - return a MessageBytes container for the header value ( existing header or new if this .
  - getValue
```
public MessageBytes getValue(String name)
```
    Finds and returns a header field with the given name. If no such field exists, null is returned. If more than one such field is in the header, an arbitrary one is returned.
  - getUniqueValue
```
public MessageBytes getUniqueValue(String name)
```
    Finds and returns a unique header field with the given name. If no such field exists, null is returned. If the specified header field is not unique then an IllegalArgumentException is thrown.
  - getHeader
```
public String getHeader(String name)
```
  - removeHeader
```
public void removeHeader(String name)
```
    Removes a header field with the specified name. Does nothing if such a field could not be found.
    
    Parameters:
    name - the name of the header field to be removed

Class MimeHeaders

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_HEADER_SIZE

Constructor Detail

MimeHeaders

Method Detail

setLimit

recycle

clear

toString

size

getName

getValue

findHeader

names

values

addValue

addValue

setValue

getValue

getUniqueValue

getHeader

removeHeader