DatabaseCache

java.lang.Object
- de.umass.lastfm.cache.Cache
- - de.umass.lastfm.cache.DatabaseCache

```
public class DatabaseCache
extends Cache
```
Generic class for caching into a database. It's constructor takes a Connection instance, which must be opened and closed by the client. SQL code used in this class should work with all common databases (which support varchar, timestamp and longvarchar datatypes).
For more specialized versions of this class for different databases one may extend this class and override methods as needed.

Author:

Janni Kovacs

Field Summary

Fields
Modifier and Type Field and Description

protected java.sql.Connection conn

protected static java.lang.String TABLE_NAME

Fields
Modifier and Type	Field and Description
`protected java.sql.Connection`	`conn`
`protected static java.lang.String`	`TABLE_NAME`

Constructor Summary

Constructors
Constructor and Description

DatabaseCache(java.sql.Connection connection)

Constructors
Constructor and Description
`DatabaseCache(java.sql.Connection connection)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`clear()` Clears the cache by effectively removing all cached data.
`boolean`	`contains(java.lang.String cacheEntryName)` Checks if the cache contains an entry with the given name.
`protected void`	`createTable()`
`boolean`	`isExpired(java.lang.String cacheEntryName)` Checks if the specified entry is expired.
`java.io.InputStream`	`load(java.lang.String cacheEntryName)` Loads the specified entry from the cache and returns an InputStream to be read from.
`void`	`remove(java.lang.String cacheEntryName)` Removes the specified entry from the cache if available.
`void`	`store(java.lang.String cacheEntryName, java.io.InputStream inputStream, long expirationDate)` Stores a request in the cache.

Methods inherited from class de.umass.lastfm.cache.Cache
createCacheEntryName, getExpirationPolicy, setExpirationPolicy, setHashCacheEntryNames

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

- Field Detail
  - TABLE_NAME
```
protected static final java.lang.String TABLE_NAME
```
    See Also:
    
    Constant Field Values
  - conn
```
protected java.sql.Connection conn
```
- Constructor Detail
  - DatabaseCache
```
public DatabaseCache(java.sql.Connection connection)
              throws java.sql.SQLException
```
    Throws:
    
    java.sql.SQLException
- Method Detail
  - createTable
```
protected void createTable()
                    throws java.sql.SQLException
```
    Throws:
    
    java.sql.SQLException
  - contains
```
public boolean contains(java.lang.String cacheEntryName)
```
    Description copied from class: Cache
    
    Checks if the cache contains an entry with the given name.
    
    Specified by:
    
    contains in class Cache
    
    Parameters:
    
    cacheEntryName - An entry name
    
    Returns:
    
    true if the cache contains this entry
  - load
```
public java.io.InputStream load(java.lang.String cacheEntryName)
```
    Description copied from class: Cache
    
    Loads the specified entry from the cache and returns an InputStream to be read from. Returns null if the cache does not contain the specified cacheEntryName.
    
    Specified by:
    
    load in class Cache
    
    Parameters:
    
    cacheEntryName - An entry name
    
    Returns:
    
    an InputStream or null
  - remove
```
public void remove(java.lang.String cacheEntryName)
```
    Description copied from class: Cache
    
    Removes the specified entry from the cache if available. Does nothing if no such entry is available.
    
    Specified by:
    
    remove in class Cache
    
    Parameters:
    
    cacheEntryName - An entry name
  - store
```
public void store(java.lang.String cacheEntryName,
                  java.io.InputStream inputStream,
                  long expirationDate)
```
    Description copied from class: Cache
    
    Stores a request in the cache.
    
    Specified by:
    
    store in class Cache
    
    Parameters:
    
    cacheEntryName - The entry name to be stored to
    
    inputStream - An InputStream containing the data to be cached
    
    expirationDate - The date of expiration represented in milliseconds since 1.1.1970
  - isExpired
```
public boolean isExpired(java.lang.String cacheEntryName)
```
    Description copied from class: Cache
    
    Checks if the specified entry is expired.
    
    Specified by:
    
    isExpired in class Cache
    
    Parameters:
    
    cacheEntryName - An entry name
    
    Returns:
    
    true if the entry is expired
  - clear
```
public void clear()
```
    Description copied from class: Cache
    
    Clears the cache by effectively removing all cached data.
    
    Specified by:
    
    clear in class Cache

Class DatabaseCache

Field Summary

Constructor Summary

Method Summary

Methods inherited from class de.umass.lastfm.cache.Cache

Methods inherited from class java.lang.Object

Field Detail

TABLE_NAME

conn

Constructor Detail

DatabaseCache

Method Detail

createTable

contains

load

remove

store

isExpired

clear