http断点续传简单实现（java)

/* Dcgo%F-W  
**SiteFileFetch.java P/eeC"  
*/ -`h)$&,  
package NetFox; )qw&%sO +  
import java.io.*; CY5Z{qiX  
import java.net.*; ITI)soa~  
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public class SiteFileFetch extends Thread { U?Zq6_M&  
}o(-=lF  
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SiteInfoBean siteInfoBean = null; //文件信息Bean EW OVx*l  
long[] nStartPos; //开始位置 <iC(`J$D  
long[] nEndPos; //结束位置 j</: WRA`]  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 g*_&  
long nFileLength; //文件长度 %ntRG!  
boolean bFirst = true; //是否第一次取文件 /$?}YL,  
boolean bStop = false; //停止标志 Xl#ggub?  
File tmpFile; //文件下载的临时信息 A?P_DA  
DataOutputStream output; //输出到文件的输出流 r),kDia  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） k="i;! Ge  
public SiteFileFetch(SiteInfoBean bean) throws IOException +I|vzz`ZVr  
{ KkbDW3-  
siteInfoBean = bean; 7Ovi{xd@  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ^jZbo{  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Ow,w$0(D  
if(tmpFile.exists ()) [RhO$c$[\  
{ |/{=ww8|  
bFirst = false; SY\ gXO8k  
read_nPos(); ",; H`V  
} 
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else 8cIKvHx  
{ Ve; n}mJ?  
nStartPos = new long[bean.getNSplitter()]; / zPO  
nEndPos = new long[bean.getNSplitter()]; @qAS*3j  
} *^ZV8c}  
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} JK5gQ3C[  
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public void run() VpDbHAg  
{ h*](a_0  
//获得文件长度 iqWQ!r^  
//分割文件 ggR.4&<  
//实例FileSplitterFetch gjDHo$  
//启动FileSplitterFetch线程 HIZe0%WPw  
//等待子线程返回 2^nxoye  
try{ !Wnb|=j  
if(bFirst) 0M[EEw3  
{ lRFYx?y  
nFileLength = getFileSize(); `d}2O%P  
if(nFileLength == -1) ukyZes8o K  
{ /*
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System.err.println("File Length is not known!"); /h3RmUy   
} h S&R(m  
else if(nFileLength == -2) +cN8Y}V  
{ X l5 A 'h  
System.err.println("File is not access!"); 1mG-}  
} 2P0*NQ  
else s;Q!X ?Q  
{ @\#td5'  
for(int i=0;i<nStartPos.length;i++) /PIcqg  
{ }o`76rDN  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); (f"4,b^]  
} _q-*7hCQ`  
for(int i=0;i<nEndPos.length-1;i++) `b$.%S8uj=  
{ !+v$)3u9  
nEndPos = nStartPos[i+1]; o>pJPV  
} 0@oJFJrO  
nEndPos[nEndPos.length-1] = nFileLength; ud('0r',D  
} *$g-:ILRuZ  
} uVrd i?3  
 }.6[qk  
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//启动子线程 v.qrz"98-  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; &tj!*k'  
for(int i=0;i<nStartPos.length;i++) P&LsVR{#  
{ FQ\h4` >B  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), /%^#8<=|U  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 3[*}4}k9  
nStartPos,nEndPos,i); H4+i.*T#  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ep{FpB  
fileSplitterFetch.start(); ]h5tgi?_l  
} eJ-nKkg~a  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), C,4e"yynb  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); fz "Y CHe  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 61U09s%\0  
nEndPos = " + nFileLength); .Z *'d  
// fileSplitterFetch[nPos.length-1].start(); N;`n@9BF  
8Zd]wYO  
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//等待子线程结束 0o&5]lEe  
//int count = 0; ]D\D~!R  
//是否结束while循环 VI*$em O0  
boolean breakWhile = false; l*G[!u  
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while(!bStop) ;aVZ"~a+\  
{ Ig{0Z">  
write_nPos(); dSHDWu&  
Utility.sleep(500); AA>P`C$&M  
breakWhile = true; 2D5StCF$O  
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for(int i=0;i<nStartPos.length;i++) ]7A'7p$Y  
{ !j-Z Lq:;  
if(!fileSplitterFetch.bDownOver) G 01ON0  
{ A,!-{/wc  
breakWhile = false; &$H!@@09|w  
break; =7UsVn#o  
} "\yT7?},  
} 2GG2jky{/  
if(breakWhile) zfdl45  
break; VUuE T  
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//count++; #GFr`o0$^  
//if(count>4) @
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// siteStop(); <:CkgR$/{  
} ))Za&S*<  
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System.err.println("文件下载结束！"); }x,S%M-  
} apn*,7ps65  
catch(Exception e){e.printStackTrace ();} 1|:KQl2q  
} UPGtj"2v-  
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//获得文件长度 
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public long getFileSize() #<x
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{ ^<6[.)  
int nFileLength = -1; gRzxLf`K  
try{ VIb
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URL url = new URL(siteInfoBean.getSSiteURL()); E{vbO/|kf  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 3OB"#Ap8<  
httpConnection.setRequestProperty("User-Agent","NetFox"); &7s.`  
4skD(au8  
y
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int responseCode=httpConnection.getResponseCode(); e|r`/:M  
if(responseCode>=400) x?<FJ"8"k  
{ MHwIA*R  
processErrorCode(responseCode); A@u@ift  
return -2; //-2 represent access is error N$tGQ@  
} *n!J=yS  
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String sHeader; Iga024KR  
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for(int i=1;;i++) 0*v2y*2V  
{ Gq P5Kx+=  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); $:^td/p J  
//Utility.log(in.readLine()); ,#K'PB4E  
sHeader=httpConnection.getHeaderFieldKey(i); [D1Up  
if(sHeader!=null) 19] E 5'AI  
{ !<h)w#>en  
if(sHeader.equals("Content-Length")) xyxy`qRA  
{ @(lh%@hO  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 7|H$ /]  
break; }QmqoCAE~m  
} (h `V+  
} !n%j)`0M  
else nr3==21Om4  
break; z@j8lv2j1  
} H,NF;QPPC  
} rT>wg1:  
catch(IOException e){e.printStackTrace ();} Alq(QDs  
catch(Exception e){e.printStackTrace ();} qxj(p o  
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Utility.log(nFileLength); V.2_i*  
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return nFileLength; FGkVqZ Y2?  
} |l!aB(NW  
7[wPn`v2  
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//保存下载信息（文件指针位置） D/' dTrR  
private void write_nPos() Qg/rRiV  
{ 4P
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try{ C9;kpqNG#u  
output = new DataOutputStream(new FileOutputStream(tmpFile)); c*M}N?|6  
output.writeInt(nStartPos.length); ,"ql5Q4  
for(int i=0;i<nStartPos.length;i++) "Rl}VeDY  
{ K<J9~  
// output.writeLong(nPos); DaVa}  
output.writeLong(fileSplitterFetch.nStartPos); LIrb6g&xj_  
output.writeLong(fileSplitterFetch.nEndPos); !_(Tqyg&  
} 
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output.close(); A%-6`>  
} `$NP>%J-  
catch(IOException e){e.printStackTrace ();} BJ0?kX@  
catch(Exception e){e.printStackTrace ();} %|4UsWZ  
} Y9|!+,  
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//读取保存的下载信息（文件指针位置） wyG;8I  
private void read_nPos() yDS4h(^  
{ nRY5xRvK  
try{ :hA#m[  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ~)'k 9?0  
int nCount = input.readInt(); rM"l@3hP  
nStartPos = new long[nCount]; c[e}w+uB  
nEndPos = new long[nCount]; !&\INl-Z  
for(int i=0;i<nStartPos.length;i++) tnIX:6  
{ -$@h1Y
 
nStartPos = input.readLong(); .e5Mnd%$M  
nEndPos = input.readLong(); j|Q-*]V
 
} C7?/%7{  
input.close(); et+0FF ,  
} w#J2 wS  
catch(IOException e){e.printStackTrace ();} ?fS9J  
catch(Exception e){e.printStackTrace ();} PaN"sf  
} ]%(2hY~i  
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private void processErrorCode(int nErrorCode) H[|~/0?K  
{ ?1".;foZ  
System.err.println("Error Code : " + nErrorCode); Dhv3jg;lq  
} B1Oq!k  
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=Runf +}  
//停止文件下载 LHmZxi?  
public void siteStop() <6=c,y  
{  C.QO#b  
bStop = true; ~;]d"'  
for(int i=0;i<nStartPos.length;i++) mcok/,/  
fileSplitterFetch.splitterStop(); "ITIhnE  
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} D#z:()VT(  
} ze;KhUPRm  
//负责部分文件的抓取 -{_PuJ "  
**FileSplitterFetch.java ?hM64jI|  
*/ j~QwV='S  
package NetFox; ,2)6s\]/b  
lys#G:H]  
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import java.io.*; }&3~|kP~O  
import java.net.*; q,6DEz  
P }uOJVQ_  
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public class FileSplitterFetch extends Thread { {_dvx*M  
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String sURL; //File URL 4`R(?  
long nStartPos; //File Snippet Start Position RrgGEx  
long nEndPos; //File Snippet End Position .[ mRM  
int nThreadID; //Thread's ID *9i{,I@  
boolean bDownOver = false; //Downing is over KGpA2Nx  
boolean bStop = false; //Stop identical ]:\dPw
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FileAccessI fileAccessI = null; //File Access interface .x1NWGDn  
KYN0  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException jA/w|\d!  
{ -!9G0h&i|  
this.sURL = sURL; nxHkv`s k  
this.nStartPos = nStart; Y4(  
this.nEndPos = nEnd; llsfTrp  
nThreadID = id; *\q d  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 MJrR[h]  
} YAmb`CP  
>"<Wjr8W!$  
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public void run() EZ`{
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{  RX5dO%  
while(nStartPos < nEndPos && !bStop) CWS4lx  
{ b_):MQ1
{  
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try{ V470C@  
URL url = new URL(sURL); +t;7tQDVB  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Xs?o{]Fe  
httpConnection.setRequestProperty("User-Agent","NetFox"); "wHFN>5B  
String sProperty = "bytes="+nStartPos+"-"; 8e|%M  
httpConnection.setRequestProperty("RANGE",sProperty); :/Qq@]O>  
Utility.log(sProperty); !?gKqx'T$  
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InputStream input = httpConnection.getInputStream(); IaXeRq?<  
//logResponseHead(httpConnection); fd2T=fz-  
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byte[] b = new byte[1024]; 6K<K  
int nRead; #C3.Jef  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) l/awS!Q/nF  
{ O8.5}>gDn.  
nStartPos += fileAccessI.write(b,0,nRead); "w.3Q96r  
//if(nThreadID == 1) &`XV
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ?K\axf>F  
}
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Utility.log("Thread " + nThreadID + " is over!"); IB7E}56l  
bDownOver = true; #Vha7  
//nPos = fileAccessI.write (b,0,nRead); Qz N&>sk"  
} E\,
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catch(Exception e){e.printStackTrace ();} 1y4  
} fwf$Co+R:*  
} $p?aVO  
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//打印回应的头信息 H'hpEwG  
public void logResponseHead(HttpURLConnection con) zI<<Q2  
{ Z/;aT -N  
for(int i=1;;i++) I(0~n,=j  
{ iW /}#  
String header=con.getHeaderFieldKey(i); 9p2&)kb6  
if(header!=null) Q)[C?obd v  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); > "=>3  
Utility.log(header+" : "+con.getHeaderField(header)); HoL Et8Q  
else 3kMf!VL  
break; FG*r'tC~r  
} 7x4PaX(  
} t1y4 7fX6  
J S_]FsxD  
#?9;uy<j.q  
public void splitterStop() *ppffz  
{ \)?HJ  
bStop = true; "!%l/_p?  
} nQ,HMXj  
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} ~O&:C{9=  
)/?$3h;  
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/* V% 6I\G2/:  
**FileAccess.java ={wcfhUl+  
*//文件访问(定位，写) 8eHyL  
package NetFox; s6^>F/x  
import java.io.*; 3x'|]Ns  
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public class FileAccessI implements Serializable{ h{HHLR  
R',rsGd`6j  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ^qD$z=z-  
RandomAccessFile oSavedFile; cq/$N  
long nPos; 'u |c  
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public FileAccessI() throws IOException ByNn  
{ 9e,0\J  
this("",0); l&Q`wR5e
 
} h'&%>Q2  
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public FileAccessI(String sName,long nPos) throws IOException =w 2**$  
{ l#Y,R 0  
oSavedFile = new RandomAccessFile(sName,"rw"); o
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this.nPos = nPos; aH/ k
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oSavedFile.seek(nPos); FSW_<%  
} <+vw@M  
+Kbjzh3<wG  
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public synchronized int write(byte[] b,int nStart,int nLen) F%D.zvKN  
{ y''z5['  
int n = -1; X
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try{ &H/'rd0M  
oSavedFile.write(b,nStart,nLen); S8j{V5R'  
n = nLen; iN8zo:&Z  
} M{T-iW"  
catch(IOException e) 4-H+vNG{%  
{ Cl8Cg~2  
e.printStackTrace (); fN^8{w/O  
} )g#T9tx2D  
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return n; CxOob1@  
} dufu|BL|}  
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} EC!02S  
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/* 3E
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**SiteInfoBean.java a>I+]`g  
*/ _ y8Wn}19f  
package NetFox; 'Nnzk  
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public class SiteInfoBean { O$j7i:G'5  
'3DXPR^B6  
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private String sSiteURL; //Site's URL PB`Y g  
private String sFilePath; //Saved File's Path jrr*!^4|  
private String sFileName; //Saved File's Name Mhf5bN|wQ  
private int nSplitter; //Count of Splited Downloading File n QZwC  
,I(d6  
/quc}"__  
public SiteInfoBean() `yXg{lk  
{//nSplitter的缺省值为5 }DfshZ0QM  
//default value of nSplitter is 5 [KaAXv .X  
this("","","",5); ^-Kf']hU  
} V0.vQ/  
jaMjZp;{(  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) suiS&$-E  
{ /dQl)tL  
sSiteURL= sURL; sF?TmBQ*  
sFilePath = sPath; udUyh%n  
sFileName = sName; pVw}g@<M  
this.nSplitter = nSpiltter; BmMGx8P  
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} FvXZ<
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public String getSSiteURL() 0s3%Kqi[  
{ g:D>.lKd  
return sSiteURL; -)]Yr #Q  
} e
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public void setSSiteURL(String value) [-k  
{ m^f0V2M_  
sSiteURL = value; (%e.:W${  
} 2%@4]  
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public String getSFilePath() 8Pn#+IvCE  
{ mD0f<gJ1  
return sFilePath; m=A(NKZ  
} M!A}NWF  
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;F!5%}OcL%  
public void setSFilePath(String value) RJ ||}5  
{ aS{n8P6vW  
sFilePath = value; ;I 9&]
 
} 6YLj^w] %  
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!&ayYu##{  
public String getSFileName() nE&@Q  
{ >:S?Mnv6  
return sFileName; ZaDyg"Tw+  
} # 448-8x  
zRl3KjET  
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public void setSFileName(String value) k_q
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{ qL&[K>2z  
sFileName = value; }Jve cRtg1  
} W*4-.*U8a  
ox>^>wR*  
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public int getNSplitter() m!4ndO;0vh  
{ Ins`l  
return nSplitter; uK#4(eY=W  
} dTC7Fm  
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public void setNSplitter(int nCount) T`.O'!  
{ $L>@Ed<  
nSplitter = nCount; w%VU/6
~  
} tl4V7!U@^z  
} =J]]EoX/  
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*,)Md[  
/* :q7Wy&ow  
**Utility.java k\YG^I  
*/ axRV:w;E<  
package NetFox; eV"h0_ox  
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public class Utility { Xy&A~F  
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public Utility() M~#gRAUJ  
{ Xe'x[(l  
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} !/*\}\'4  
r CHl?J  
//线程睡眠 JEwa
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public static void sleep(int nSecond) @=Uh',F  
{ d(x\^z  
try{ A*R^n}sh  
Thread.sleep(nSecond); |y# Jx  
} *74MWF@IY  
catch(Exception e) }wjw:M  
{ "3"V3w  
e.printStackTrace (); N1S{suic  
} vq0Tk bzs  
} Oo8VeRZ  
&yTqZ*Yuk  
//日志 p* (JjH  
public static void log(String sMsg) Lpz>>}  
{ ,GIyq)  
System.err.println(sMsg); `?qF$g9u~  
} n;Q7X>-f8`  
g i-$ZFzB  
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public static void log(int sMsg) qI9z;_,gNz  
{ K5VWt)Z#  
System.err.println(sMsg); m6K}|j  
} Bz-c$me1  
} S_4?K)n #  
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/* UiP"Ixg6  
**TestMethod.java
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*/ f#"J]p  
package NetFox; T|op$ s|  
fS:&Ak ];  
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public class TestMethod { l^-];|Y  
YQ)kRhFA  
 c(E{6g?  
public TestMethod() v2\FA(BPn  
{ ///xx/weblogic60b2_win.exe )Y0!~# `  
try{ (ejvF):|  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ")5":V~fN  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Al^d$FaF  
SiteFileFetch fileFetch = new SiteFileFetch(bean); J26VnK  
fileFetch.start(); {n.PF8A5X  
}  6f>{"'  
catch(Exception e){e.printStackTrace ();} 9Cp-qA%t  
;_I8^?d  
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} ?V.cOR`6  
SrJGTuXg  
@6sqMw}  
public static void main(String[] args) e@07  
{ E\EsWb  
new TestMethod(); v`x.)S1  
} 1Z2HUzqh.  
} 6=/F$|  
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